Probably old self proclaimed tech news sites because goog doesn't give good search results any more, or at all in the past decade or so.

Well, I know for a while Steam only officially supported Ubuntu, and on their developer page It still mentions that they only support Ubuntu, though I don't know if they've just forgotten to update the page:

Steam only officially supports Ubuntu running Ubuntu 12.04 LTS or newer and SteamOS, but the Steam for Linux community is extremely resourceful and has managed to run Steam on a large variety of distros. Valve approves of these efforts but does not officially endorse or provide support for them.

Perhaps being one of the first major Distros in the sense of being easy enough for many less tech inclined to switch from windows and not need to know as much command line.

I had tried older and other versions of Linux but back then Ubuntu mostly just worked. Being a leader in that sense has held them in the place where its safe to dive into Linux despite the various other flavors that can do it better. The PR is a lot to overcome for newbies that are overwhelmed on it. It's only later after getting a footing you will be brave enough to try over flavours.

For me Linux Mint is a no brainer place to start with my older hardware than Ubuntu now but I don't think they have the word of mouth like Ubuntu. At least with Ubuntu if they are even aware of something more than Mac or Windows they have probably heard of the name not really knowing what it is. Many aren't Googling Arch for first time installs I suspect.

To add to what @Grass wrote:

- Ubuntu has never been a good distro for gaming. The main reason being their outdated packages in their default repos. As a result, you're always missing out on all the latest developments and advancements in Linux gaming - the Linux world moves really, really fast, and each month you get new versions of Wine, your graphics drivers, kernel advancements etc that improves system performance and game compatibility - but you won't get to enjoy any of these features until the next major release of Ubuntu. Also, for some folks, having the newest kernel/mesa (graphics) etc is a necessity if they've got recent hardware and they want to make the most of it. To address these limitations, people have created their own repositories (ppas) containing up-to-date packages, such as the Oibaf repo, but the problem is that these repos tend to break your system, especially when the time comes to do an OS update/upgrade, which is why we do not recommend anyone to use these repos. But as a result, you'll be stuck with an outdated system, and sometimes that means you won't be able to enjoy playing some games because you're stuck on some old version of something where your favorite game doesn't work.

- Ubuntu hasn't been a good distro in general for a long time now - this goes back to more than a decade ago when they made the controversial decision to switch their default DE to their in-house developed Unity, instead of continuing to use Gnome. Unity was, at the time, bloated and clunky, and many people felt it was a wasted effort. Eventually Ubuntu abandoned Unity and adopted Gnome, and the whole community laughed at them like "lol, we told you so". This sort of pattern continued pretty much constantly, where Ubuntu would choose to go for their own, often inferior, in-house solutions - such as Mir instead of Wayland, Upstart instead of systemd, Snap instead of Flatpak etc. The most recent anger from the public comes from their decision to force Snap packages as the default over native packages (when most people prefer either native or Flatpak packages), and the taking over of LXD. In addition to such unpopular decisions, they've been criticized for including bloatware such as Amazon search, unwanted telemetry, or just the general bloat of unwanted apps and services that come by default, compared to stock Debian. Basically, Ubuntu has become the Windows Visa/8/11 of the Linux world.

- There are plenty of gaming oriented distros these days that are a much, much, better choice. These distros come with a gaming-optimised kernel, plus the newest mesa/wine/codecs/drivers out-of-the-box, and they include configs to make things like the newest game controllers and other gaming hardware work properly. Examples of such distros include Nobara, Bazzite, ChimeraOS etc. Or even a general distro such as Fedora, Pop!_OS, EndeavourOS, CachyOS etc would still be a much, much better choice than Ubuntu.

Honestly not really, but on top of recent hate due to snap and etc, I have deeper rooted frustrations from the pre-proton era and having to suffer through dependency hell with ppa and such when trying to use bleeding edge packages to get things working and squeeze out individual frames per second, plain debian not being much better at the time, and just getting old and not even having the patience to slamy keyboard any more.