But in Android/iOS you can install apps.

The apps do not install or update any included libraries in the base image of the OS. It may rely on an specific or minimum version of the OS but that's it. Everything the software needs is installed into its own sandbox, and other applications cannot share it.

Ok. This makes me wonder:

The original idea of shared libraries was that a computer system can save time and memory because they only need to be loaded once.

Is that idea dead?

If you want effective sandboxing, yeah.. pretty much. If no one can agree on which version of the library you're provided, then bring your own.

We should go back to static linking. With CI/CD generating new packages is trivially easy.

Then we can throw out all these fancy packaging tools like Snap and Flatpak, all the fancy half-done COW filesystems like Btrfs, all the fancy hidden-delta-synching stuff like OStree, and just ship one honking great binary in a single file that works on anything, no matter what the libc so it even works on musl or whatever.

Ha ha, only serious.