Higher memory consumption as a trade off for developer convenience might be questionable in many cases but here it is to increase USER convenience.

What are developers supposed to ship their apps with? Make packages for every Linux distribution under the sun? Flaktpaks and Appimages solve a real problem. The current alternative is NOT being able to use the specific software at all because you don't have the right version of Ubuntu.

Maybe Guix/Nix are solutions for some of the pain points of traditional package management. And yes, libraries really need to focus on backwards compatibility. In the meantime, AppImage/Flatpack gets the job done. I am not out of luck when my distro does not offer the right package with the right version.