Personally I don't want FlatPak either except maybe for 1 or 2 apps where the sandboxing actually makes sense. It's still a waste of resources just to appease lazy maintainers.

Ubuntu went totally overboard with their snaps, putting everything in it trying to force it to become a standard. But FlatPak is not great either even though it is an open standard.

It's nice for the 1 or 2 niche apps that aren't available any other way, but for the most part I prefer normal packages.