Distros generally build everything they can as modules these days, including filesystems. No reason not too, we've had initramfs since forever; you can't build everything in that anyone might need to boot their machine.

As long as the testing pipelines are in place to make sure the dkms module builds on every distro configuration (a good chunk of that is still manual, but there's a project to improve the test infrastructure) - in practice, no one will notice.

I wouldn't have noticed the DKMS switch on my NixOS laptop if I didn't know it was happening.