It's the second biggest Linux company behind Redhat, so I think it's reasonably popular. It's also been a while since I used it, but I'll also point out that it's developed primarily in Germany, so it's entirely possible it's just not as popular in the English speaking community.

However, the licensing agreement with Microsoft put many people in the open source community off, so I think that's contributed to its decline among hobby users.

Ubuntu does a pretty good job marketing-wise, many people start they journey with Ubuntu and never look for other distros. Or on the other hand, they end up on advanced/continuous-maintenance distros like Arch Linux.

Do you really think 'continuous maintenance' is an appropriate category for Arch? That hasn't been my experience.

If you go to an Arch community and you say you haven’t updated your system in a month, they will be mad.