They did: Lefthook lets you define a "group" where you can specify that every command should be done in parallel: https://lefthook.dev/configuration/group.html. In addition, it's possible to configure the whole hook to run in parallel through another property: https://lefthook.dev/configuration/parallel.html.
I'm assuming that Hk's innovation here is that it's a bit smarter with what it runs in parallel. Maybe it uses the globs to automatically run commands in parallel which targets different files?
> "Rust is faster" as an off the cuff comment that should have been left out seeing it has triggered some folks to hyper focus on that point.
It's not a a hyper focus: This was the first reason (out of only three) that Hk itself presented as a reason to use it over Lefthook. So yes, I agree: It should have been left out if the intention wasn't for people to focus on it. Put it somewhere in a footnote if it's not so relevant.