A lot of it is momentum / inertia? (I can't think of the right word).

Basically, Ubuntu was the distro for years. It was the one that just worked and was easy for new users. It built on Debian's stability and made everything easier. All the beginner guides and how to guides were written with Ubuntu in mind, so lots of new users switched to it too.

Mint built on Ubuntu's success, and made things even easier for people switching from Windows, by doing things like putting the start menu in the same place, and making everything look familiar. Because it's based on Ubuntu, the guides all still work too. As Canonical started making unpopular decisions with Ubuntu, Mint took the lead as the distro to switch to.

Now, other distros like Fedora, and DEs like KDE have caught up, and even passed Mint for ease of use, that history is hard to overcome :)

That's why we call them flavors. People like certain flavors. It doesn't mean the nutrition is any different or that you need to always use only whatever flavor is somebody else's favourite. The lovely thing about Linux is the freedom to choose and to try different things to find what works best for you personally. There's no organization trying to shove certain tools and principles down your throat for profit. It's literally just personal preferences and they're all equally valid choices. We try to make recommendations on things that might be easier to grasp or might suit a person's situation better but really they're all just flavors and they're all good for the people who like those flavors.

Why are there so many different types of bread at the store? Or mustard, ketchup, milk...etc.

It's mostly personal preference and reputation. Ubuntu has a shit reputation right now because of some poor decision making, and Fedora has a solid reputation and doesn't cause problems.

That's pretty much it.

What is missed is not necessary or available.

For some people, the differences can be deal breakers. Nix is interesting, but I won't likely move away from Arch because access to the AUR is more valuable to me.

Honestly the difference on the whole is preference. Maybe the availability of things in the repo but with flatpak that feels less important than it did a few years ago. I run Fedora on my laptops and bazzite on my Ally

usually mint is focused on because it's a simple enough ui for those new to linux. it doesn't mean other distros are forgotten. it's usually just for those not familiar with linux or coming from a different OS.

Honestly, I don't think it makes a huge difference for desktop users. I use Nobara because it has built in comparatively out of the box. I also run Fedora 42. All work pretty well.