oh. I understand why that's the default, but it should be possible to dynamically link musl on a distro like Alpine, right?

Musl supports dynamic linking. But it also supports static linking (which glibc doesn't really support because of NSS and similarly fun features) -- hence why Rust requires musl to statically link Rust binaries.

My understanding is that there’s some complications there, but I’m not fully aware of all the details, honestly.