Its not needed since most linux software is open source and gets packaged properly for each distro.

And when it isn't one of those things, well, fuck you I guess. That's one of the biggest reasons I think a lot of people don't use Linux, yet the Linux Desktop community consistently ignores and dismisses the issue and then wonders why Linux Desktop isn't more popular.

Flatpak exists to solve this problem.

Flatpak unfortunately has other issues inherited from a repo-based approach. Like, it can't be installed to a separate disk than the rest of the system and you can't use anything not in your repo, forcing you to setup pretty much 1 repo/application, which is ridiculous.

That didn't stop macos or android devs from uploading their apps to the play store and app store.

Oh you mean those stores developers are constantly complaining about because of entry barriers and having no recourse when their software is arbitrarily booted out? Or the ones where users complain that they can't get older versions of software and have difficulty legitimate apps in seas of fakes?

Repo models are antithetical to the concept of personal computing in my opinion.

It could of course, see for example any big commercial software like Mathematica, Matlab etc. . However, doing things that way is something you really, really want to avoid if at all possible.

Why? Because it actually works and makes things simple instead of causing a giant headache for users? Because it gives users the power to consume software directly from developers, cutting out a third party repo maintainer?

Yeah sure, those are obviously the reasons.

You get this with Snaps, Flatpak and AppImages

I'd argue you really only get it with AppImage, which is treated like garbage by the community as a whole.

Aah no!