Dynamic swap and zswap aren’t really the same as efficient ram usage it’s just good ways to mitigate when you run out.

I disagree. If the OS automatically identifies unneeded pages and compresses them or swaps them out, it’s certainly using the physical memory more efficiently than if it wasn’t doing these things.

avoiding multiple versions of the same library is what distros exist for

But they can’t if the applications they want to ship don’t all use the same version. E.g. Ubuntu ships GTK 2, 3, and 4. Arch even still ships GTK 1 in addition to these three.

avoiding loading different frameworks is what Desktop Environments are for

What happens is you run KDE but then you still want to run Firefox so you still need GTK.