True, I barely ever use them (Yubikey manager is most easily offered via AppImage). I only actively use Flatpaks. I think AppImages should exist though, as the portability aspect could be useful (Syncthing syncing a directory with all your applications to different machines, etc.)
The advantages you speak about AppImages quickly fade away when you consider how much slower apps launch.
True, I barely ever use them (Yubikey manager is most easily offered via AppImage). I only actively use Flatpaks. I think AppImages should exist though, as the portability aspect could be useful (Syncthing syncing a directory with all your applications to different machines, etc.)