###tl;dr: No, this site is about official Ubuntu flavours exclusively and it should stay this way.
This is Ask Ubuntu, part of the StackExchange network. In this whole network, the scope of a site is what defines it. The scope, most importantly which questions you may or may not ask on the site, is the first thing which must be defined for a site during its Definition phase on Area 51, long before it goes live. AU is about “[u]sing and administering official Ubuntu flavors”, and explicitly not about using “other Linux distributions”, questions about which you may not ask here:on-topic
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This is Ask Ubuntu.
1. Other distributions and even Ubuntu derivatives are not the same as Ubuntu.
They use different packages, from different software sources and typically built differently. They are configured differently. Their principles and goals overlap with but are not the same as the principles and goals of the Ubuntu project.1
This pertains to even the most basic software, let’s just take a look at the coreutils package: Currently supported Ubuntu versions ship v8.21-1, v8.25-2 and v8.28-1 whereas a current Arch Linux ships v8.30-1. How exactly do they differ? Unless you want to read hundreds of commit messages and maybe even source code diffs there’s no way to know. My bad, I forgot to copy the last part of the version numbers, actually it’s v8.21-1ubuntu5.4, v8.25-2ubuntu3~16.04, v8.28-1ubuntu1 and v8.28-1ubuntu2.
Let’s take /bin/echo as an example, that one certainly doesn’t change – or does it? On v8.21, the source file echo.c has a file size of 7630 bytes, on v8.25 it’s 7642 bytes and on v8.28 it’s 7634 bytes, whereas Arch Linux’s v8.30 echo.c has a file size of 7635 bytes. Oh wait, I totally forgot the patches Ubuntu applies to the Debian packages (see long version numbers above), of course we need to check those as well…
Another example of huge differences between software versions is the recent case of ls quoting filenames in 18.04, a behaviour which baffled Ubuntu users while Arch Linux users are long used to it.
Even most basic commands, though of course called the same, are different from system to system, unless the systems involved share the same package sources.
Ubuntu and its official derivatives (…) share package repositories, development philosophy, and substantial elements of design philosophy with Ubuntu.1
2. The policy is about operating systems, not software.
You’re trying to draw a line between software that’s Ubuntu-specific and software that’s not Ubuntu-specific. As I have shown above, that is very hard to do and gives surprising results even for basic software, it’s virtually impossible to draw this line clearly. In fact, this even pertains to the question you found poorly handled: The software in use is available both directly from github (v0.7.1) and compiled specifically for Ubuntu in a PPA (v0.7.1-0ubuntu3~ubuntu18.04.1), as the version numbers tell the Ubuntu version is different in a way again only code diffs can show. We can never be totally sure these differences are irrelevant to the question.
How do we define our scope then? Simple: We limit ourselves to questions about using Ubuntu and its official derivatives.
This site is only about Ubuntu. Yes, that is often a silly distinction since 90% of all Linux stuff is common to any distribution, but if we don't want this site to cover all Linux flavors, the only way to draw the line is "Ubuntu == on topic" and "not Ubuntu == off topic". Anything else essentially leads to chaos since the vast majority of people don't have the expertise needed to know that something would be the same on another distro.2
We aim help people install, use and develop on Ubuntu. It's that simple.3
This way any user, they may be asker, answerer, voter, reviewer or mod can easily determine whether a question is on or off topic here, just by reading the concise help page on-topic. No version number confusion, no code diffs, no uncertainty, no need for discussion. It’s a clear rule defining what we do here. Yes, a Linux Mint user might have exactly the same issue a Ubuntu user could have, and yes, the answer may be the exact same for both – it doesn’t matter. This is Ask Ubuntu.
3. Keeping off-topic questions hurts everyone
When AU receives an off-topic question, the usual course of action is to close the question as off-topic. The close notice gives a very good overview over other sites where the question may be on topic. Questions about other Linux distributions can often be migrated to Unix & Linux so that OP doesn’t even need to pose the question again.
3.1 Keeping an off-topic question hurts its OP
When asking a question, a user doesn’t really care about the site or the content they create, so let’s just concentrate on them and their issue for a moment.
Whether they didn’t take the tour or just don’t care of the site’s scope, although using an unsupported OS they ask a question on AU and don’t include the OS information.
Now someone answers the question – on and for Ubuntu, needless to say. Maybe this actually helps and solves OP’s problem, but because differences there’s also a notably good chance it doesn’t while on Ubuntu it would. Now in most cases OP will not let it slide, but rather post comments on the answer saying it doesn’t work, downvoting actually valuable content (“This answer is not useful”!) and in some cases even rant about getting trolled and molested by the answerer (yes, I experienced that). All that happens just because OP is asking the wrong community instead of having their question migrated to a fitting one or being pointed in the right direction. It wastes OP’s time and needlessly leads to confusion and frustration.
3.2 Keeping off-topic questions hurts our community
Writing good answers costs time, and it costs even more time when follow-up discussions with OP arise. With over 500k visits per day, AU is the third most visited site of the StackExchange network, but only two in three questions are answered, we have more than 100k unanswered questions here.4 100,000 questions which hopefully for the most part are within our scope and to this day remain unanswered. If that is the case, do we want to spend time and invest energy on off-topic questions, just for the chance that they may be applicable to Ubuntu as well? No, we hurt the community by not answering on-topic questions in this time. What we need is answers, not questions.
If we start neglecting our scope on some questions, users get the idea that we’re basically accepting everything and consequently even less care about the help pages.
“[W]e’re working together to build a library of detailed answers to every question about Ubuntu”, remember?
Anything not about Ubuntu is clutter that gets in the way of maintaining Ask Ubuntu as a resource for information about Ubuntu.1
We already get much of this clutter, encouraging users to flood AU with even more keeps us from this goal.
3.3 Keeping off-topic questions hurts other communities
Though a remarkably big and vivid one we’re not the only Linux distribution community, there’s Ask Fedora, the Linux Mint Forum and Unix & Linux not to forget, just to name a few. If we act according to our policy when we receive an off-topic question, we hopefully point OP to other communities where their question is on topic and thus help other communities build their knowledge base. If we keep it and don’t tell OP that there’s a better place to ask that question, we impertinently keep their valuable content from them, effectively stealing traffic as well. That’s certainly not the spirit.
Conclusion
This is Ask Ubuntu, it has a clear scope established for multiple very good reasons. Let’s not soften our prime policy, let’s not make it Ask Ubuntu-ish.
1: Eliah Kagan on Why are questions about (specifically) Ubuntu based distros off-limits?
2: terdon ♦ in https://chat.stackexchange.com/transcript/message/48842700#48842700
3: Oli ♦ on Are non-Ubuntu-spefic questions allowed?
4: see https://stackexchange.com/sites?view=list#traffic and https://stackexchange.com/sites?view=list#percentanswered (Scroll down, keep scrolling, keep on … If you’ve seen enough, press End and scroll up a bit, AU is on the ninth to the last place.)
