Even if you could statically link everything else you would still to dynamically link to the system's native user-mode graphics drivers, which in practice means that you also need to dynamically link to other libraries used by your application and the drivers (like glibc & libllvm) in order to maintain compatibility. Static linking against glibc isn't really recommended in any case.

Nothing prevents you from providing your own preferred versions of most of the dynamic libraries along with the application, however. It should be possible to limit external dependencies to libraries that actually care about maintaining compatibility.

Dynamic linking is usually for packages maintained by the distro, but many proprietary software actually use statically linked libraries.

This way they have one binary that runs on all the modern distributions, then packaging is only to integrate with the package system, menus and stuff (and is optional).

There's also this: https://appimage.org/

So honestly, people complaining about Linux fragmentation haven't done enough research.