You mind if I poke the subject for a little more? It is opening a new understanding for me.

Please keep in mind I'm not a programmer, to any degree.

As per what you are explaining, flatpaks working remembers me of a flower blooming on a tree: it uses resources provided by it, adds functions to it but doesn't alter it in a significant fashion.

But again on the space saving and version controlling.

Let's take a given flatpak, where 50 libraries are shipped with it to ensure it works properly, on any given distro.

As you already said, library versions between distros can vary wildly but would it be that difficult to have a script running pre installation (I think "connection" is more adequate to describe the process at this point) to check for what already available required resources exist on the system to avoid redundancies?

I can understand that by having this sort of an homeostatic environment aids in assuring a given program will be capable of running on any machine but I can't shake the intuition that at some point this will backfire. It's not hard to imagine software to be kept relying on older, perhaps unsafe or not as streamlined versions of given libraries just because the developer is not that motivated to make whatever changes necessary to keep up to date with the new versions, as their software already runs as expected.

I'll risk it and try it.