just shut up. You have no idea what you are talking about. None. ZERO.
People like you are the problem. People who trash-talk solutions without understanding the problem. Who spout bullshit about what works and doesn't work with distributions.
No, distributions do not just package something that is open source. They have their own weird ideas of how things should be. Debian is an especially terrible example; there those ideas are just braindead. "this library doesn't compile on SPARC32, it therefore must not be in Debian" - "oh we packaged a two year old version of this, that's good enough" - "oh, you, the app developer must follow our random, arbitrary, onerous rules in order for us to package your software".
Funnily Fedora is actually one of the easier ones to work with. But either way, the point is that I, as the app maintainer, don't want my app bundled in a distribution anymore. Way to much pain for absolutely zero gain. Whenever I get a bug report my first question is "oh, which version of which distribution? which version of which library? What set of insane patches were applied to those libraries?". No, Windows and Mac get this right. I control the libraries my app runs against. Period.
End users don't give a flying hoot about any of the balony the distro maintainers keep raving about. End users don't care about anything but the one computer in front of them and the software they want to run.
With an AppImage I can give them just that. Something that runs on their computer. As much as idiots like you are trying to prevent Linux from being useful on the desktop, I can make it work for my users despite of you.