The great thing about Ubuntu was that they took an awesome distro, Debian, and made it easy to install and usable out of the box. The standard Debian install experience was something like 100s of errors as you run the installer and the packages try to access something that is still half-installed or whatever, and then end result of install is text terminal. To get into X, and have hardware work, you had memorised a list of groups you need your user into, and packages to install, and if you forgot something, things would break, sometimes subtly so that you wonder what's ailing that install and why it isn't working properly.
The greatest thing Ubuntu did was get that big, high-quality debian archive into hands of the masses. They literally mailed you CDs with Linux on it for free if you asked. I adopted Ubuntu in 2011, but early adopters like me remember that it was always somewhat quirky experience. They didn't maintain the universe repositories, which is the bulk of Debian -- they simply snapshot it and said there was no support and thus no security for them. The default backgrounds contained nude women in artistic poses taken by professional photographers. There were clear cracks in the facade.
I remember the complaining was bitter from the start, from stealing the Debian's developers to work on Ubuntu, to being popular and popularising Linux to unwashed masses, to doing these women backgrounds, to literally whatever.
Canonical was always strange, for better or worse. But they did change one thing about Linux which was the default install experience: you get a working install out of the box, even with closed-source nvidia drivers included, if that's what your hardware needed.
This simple practicality, including acceptance of that closed source driver, was sorely lacking in Linux world at that time, and users did suffer for it. Fair to say they've had their good as well as bad days.
Unity Interface
According to many involved at the time, Unity was pretty much because Gnome refused to accept their patches or work with Canonical to accommodate their (reasonable) needs. They didn't intend or want to create Unity, but at the time were pushing to unify Phone, laptop, desktop etc. (hence the name). There were a lot of people at the time very fed up with what they perceived as Gnome's wilful obstructiveness and hostility at the time.
I've certainly witnessed a lot of Canonical/Ubuntu hate that's just wrong-headed, like people accusing them of creating Upstart as NIH, saying they should have used systemd (that didn't yet exist).
The defacto Industry Trend
Ecosystems develop as successful innovations at the micro level organically become more widespread as they are iterated upon and refined against real-world use cases -- things evolve toward becoming standard. But there are a lot of Organisation/People who want to jump straight from having a new idea to making it industry standard, skipping everything in between. So they attempt to experiment with drastic changes at the macro level, by forcing them into the established solutions that everyone is already using.
This is a terrible approach that diminishes the value of existing solutions without the evolutionary refinement necessary to get new solutions to the point where widespread adoption would occur naturally.
So we end up in the strange situation, where existing software is breaking for a lot of people, but there's nothing viable to replace it with. And instead of working towards that end state, proponents of new solutions try to advance them through argument, as though the functionality, reliability, and performance of software were a normative principle that you need to convince people of, rather than empirical qualities to simply be demonstrated.
"Snaps"
Canonical has pretty much always had bouts of "You are going to do things my way, AND YOU ARE GOING TO LIKE IT!!!!"... Deliberately breaking other DE/WMs so that you had to use Unity was probably the first, and there were others, but Snaps is apparently the hill they've chosen to die on.
At the end of the day, I have no use for a distro that refuses to do what I tell it to. Canonical has wired it's upgrade scripts and hacked apt to SILENTLY replace debs with snaps and even remove flatpaks and replace them with snaps.
Eventually people have their own opinions from experiences and that's fine, personally I don't mind Ubuntu server It works well and is very stable. A lot of server applications are designed with Ubuntu Server in mind as being the primary driver with little headache etc
For a desktop though I just can't help but feel Ubuntu is just a more bloated Debian Like it's just debian with a heap of stuff on it I didn't ask for or want. Why would I want to use that when I can just get Debian with gnome or KDE etc and run it bare-bones? The Debian installer nowadays is very very simple so it's not like it's even a "non-noob" version of Ubuntu.
I guess the counter argument to that is "why does it matter if it's slightly more bloated on a modern PC" Which really, it doesn't and that brings me to my final statement of "the beauty of Linux is how flexible it is, do what you want with it"
Additionally I will add that most people proficient enough in Linux to build a YouTube channel off it have a lot of experience in Linux itself and using, for lack of better words "more complete" distros don't really make sense because they already have the know how on customising the base distro to do the same and remain more lightweight