Technically, they usually aren't "statically" linked as such.

They usually use dynamic linking, but then ship those dynamically linked libraries in the package.

This has the advantage that the user can still replace the libraries if they want (e.g. for games this is sometimes useful to replace the sdl build with one with more options enabled), and I've heard rumblings that the support for static linking on linux isn't all that great.

Your knowledge is incorrect. Snaps don't have to be statically linked. They use a mount namespace with a predictable set of libraries that are maintained and receive security updates. In addition the application can bring additional libraries but those are on the application developer to maintain (or delegate to a hosted service like build.snapcraft.io to rebuild on security updates).

Sure, you can do static linking, you just don't have to and this is not how snaps work.

Thank you for correcting me. Appreciate it.

Although my point somehow still stands:

Vendors could've statically linked their apps for a long time and provided debs and rpms relatively easily for a long time.