Why not get the benefit of both worlds but having centralised repositories for Snaps/Flatpaks? This way developers simply have to push their builds to it. Of course, also retain the traditional packaging model for much of the underlying system, and we seem to have hit a sweet spot between established practise and the anarchy of Windows land.
Sure. I'm a pragmatist - if that would work, I'd be happy. One major problem is fragmentation/network effects though - you'd need to get enough developers onboard to make something effectively the 'default' userspace packaging system. Major distros already have a big NIH problem with system packaging, every one having it's own system.
Packaging is a difficult problem - the 80% use case is easy to solve, but the edge cases really require elegant forethought. It also seems that every distro has a different idea of what that 20% is...