The problem with that (now deleted) questionthat (now deleted) question wasn't mainly that it was off-topic (which it was), but that:
- It was spam, or pretty close.
- It wasn't a question at all, so much as a call for discussion. Or maybe not even that. It was essentially saying, "Hey, take a look at X!"
If the discussion had been about an official derivative of Ubuntu, it would still have been primarily opinion-based (if it was clear that no answer based on objective facts was being solicited) or unclear. Or perhaps too broad.
Anyway, it was a call for discussion about a topic, rather than a specific question. It was also off-topic, sure. It was entirely about an existing unofficial derivative of Ubuntu. But that wasn't the main thing wrong with it. Still, voting to close it for that reason was perfectly good and correct option.
As for why we have a custom-distributions tag, as Oli says, creating a custom distribution from Ubuntu is a way of using Ubuntu. Using a custom distribution, at least once it gets to the point of having its own name, being released, etc., is a way of using an Ubuntu derivative.
We have a question about this, and the votes on its answers (and absence of any answers saying questions about making custom distros should be considered off-topic) indicate pretty strongly that the current community consensus is that we will help people with specific problems or requests for information, in service of the creation of new custom distributions based on Ubuntu:
While my answer there was intended as a robust discussion from a site policy perspective, I think RolandiXor's answer clarifies best how the customization of Ubuntu, including to create a new custom distro, is a topic supported by Ubuntu help resources and in Ubuntu's documentation. Thus that answer may be what you're looking for.
