They have use cases, this just isn’t one of them. Every app doesn’t need to be a bloated mess, system libraries exist for a reason.

I’d rather run batocera in a vm than use a flatpak.

If you say that out loud you’ll skip right to the boss fight in diabolo 2

Saves Space
RetroDECK also saves space comparing to installing all emulators separately as we can cross reference libraries and functions the Emulators / Engines have in common and only ship one instead of several.

That’s called a system library…