Atomic and update speed are orthogonal. And ex. https://blendos.co/ and https://arkanelinux.org/ are atomic Arch derivatives if that's your speed. (Not explicitly endorsing either, but they're there.)
Being an https://getaurora.dev (Universal Blue based) user I don't notice updates at all. I don't update, updates happen in the background. What difference does "speed" make then?
If someone finds a security vulnerability in software you're using, it would be really nice if you could get the update in the very next reboot instead of needing to wait a few weeks for it to come through
