I asked a question
And it almost got closed/deleted/moved. Cause i didn't put in the question that i was using ubuntu
should an OPTION to add a system-info like link. like the commands in this question be available in a system-info tab. Like launchpad is using for reporting bugs!
I asked a question
What Went Wrong Here
I think the problem here was not that you didn't explicitly state you were running Ubuntu, but that people assumed you weren't running Ubuntu. That was an unreasonable assumption for them to have made. They should have asked if you were using Ubuntu instead of asserting that you weren't.
This was an especially unreasonable assumption considering that your question (even before you edited it) contained the text
My preferred music player is rhythmbox. Rhythmbox is a very popular (and the default) music player on Ubuntu, but it hardly ever used (and is hard enough to set up that it's widely considered even not to be available) for Windows or Mac OS X.
Everybody makes mistakes, and I'm not trying to attack those who made this one. Rather, I want to express that I think this is just an unfortunate error on the part of a few people who saw your question. I don't think this is a systematic flaw in AskUbuntu that would require a technical solution to correct.
However, if it turns out that this is happening all the time (and I just haven't noticed), then I would be mistaken about that, and then we should start investigating ways to mitigate it.
General Thoughts About Automatically Gathering System Info
With that said, for separate reasons, it would be convenient for AskUbuntu to automatically suggest information for someone to add to a question. For example, when asking a question about video drivers, AskUbuntu could automatically recommend that you include the output of
sudo lshw -C video. I know this isn't quite what you have in mind, plus this might be quite nontrivial to implement.
As for automatically including information, some very basic information about your system can usually be gleaned by a web site through the facilities provided by your browser. But people often post questions about different systems from the one they're using to post.
This is different from reporting bugs in Ubuntu. When a program crashes, if Apport crash reporting is enabled, Apport (which runs on your computer and is separate from your web browser) will gather information and send it to Launchpad. Then Apport will open a web browser window/tab and bring you to Launchpad, where you wait for the information to be processed and then fill out the bug report. Launchpad is not itself able to gather this information about your computer.
It might be difficult to write good client-side active content that works in multiple browsers and automatically adds information to AskUbuntu questions. It would have to have a level of access to your computer that could raise security concerns. However, browser extensions/plugins for this functionality probably could be written and made available.