Technical stuff aside, a major reason why Flatpak does not get the hate Snap does is because users don't resent it.

There are 2 things people hate: the way things are, and change.

Ubuntu put Snaps on users desktops without asking if they wanted them. They just did it, then closed off ways to opt-out/avoid them (Cf. Firefox).

Forced change fosters resentment.

No distro made Flatpaks default/required/opt-out. Users had time to come to the tech and adopt it on their own terms/needs.

Just IMO.

@omgubuntu today I was running apt upgrade and as an software 'update' i got entire new snap install of firefox. Even as I had one installed from flatpak for entire time I have this ubuntu install...
If I wanted I should be able to have it compiled from source or something else entirely. But no, ubuntu people know better whats best for me.
This approach is strikingly similar to windows and it's 'we will not let you uninstall edge'
@astromateusz @omgubuntu Also make sure to apt remove Firefox. Something probably happened with the transitional packaged that prompted the reinstall.
@that_leaflet yeah did usual purge, it's just so annoying