Also why it looks like RHEL family is completely out of fashion? Is it considered too "enterprisy"?
On the desktop, Debian has quite a few more rough edges, and you wouldn't really recommend it for a newbie.
Regarding redhat being out of fashion, part of that is that Ubuntu was a big drawcard to bring devs to linux because they focused on polishing the desktop, so the debian family got an influx of users. Personally, I don't like redhat tooling as I find them full of gotchas and their output is usually full of chaff and hard to parse. That may be just a personal taste issue; I'm sure plenty of redhat admins find debian tooling weird and odd.
On top of that, it was already a pretty popular distribution. The more people use it, the more documentation becomes available, and the more new people will pick it up.
Well, look at the website: https://www.redhat.com/en/technologies/linux-platforms/enter.... That won't appeal to anyone outside of an enterprise chair.
RHEL/CentOS is still around, but you don't hear about it too often.
PPAs.
Might be the worst solution but is the most well known.
Sure, it'd easy to set it up yourself. But the point is that PPAs are managed by someone else and have already been set up.
If I want a new software, and there's a PPA, I can just use that PPA and be able to use it straight away.