There is some drawback. The main one : app can’t communicate with each other.

Example firefox and his extension keepass. As keepass can’t communicate with firefox, you have to open both apps and switch their windows.

You can use flatseal to manage communication between apps but that’s not an easy process and may prove a security issue if you don’t understand the technical jargon.

An immutable OS that run all app whatever are their package distribution.

Later a full OS rewritten in Rust with goods tools that share folder’s content accross all devices and mass storage device as syncthing do.

Let’s imagine a button where you click on add devices, then you scan the QR code and chose which folder you want to share. :)