Almost all desktop apps are newer version from flatpak than from repos of my latest Debian.
I understand. For coder is much easier to test one version than all available distros.
And for maintainers the same. Too much apps to test.
Flatpak/AppImage/snap creates mess in system (oh, snap!) but for user it's a way to have good working environment.
Don't hesitate to use it. 

 I remove Snap from Ubuntu and lock it out so it can't be reinstalled in a system upgrade.

 

 I don't like it too. Have it on the working notebook with corporate image. Using flatpak at home.

But. To be ordinary Ubuntu user (who never run "mount" command), it's better to use snap than years old apps versions. 

 You don't have to use old apps. You can get everything through PPA, flatpak, and appimage. 

 I just didn't get your point as you are writing exactly the same as me.