It isn't picking nits, git does patch management, there is nothing and shouldn't be for review.

It matters because where you assign your responsibilities is the difference between spaghetti code/architecture and a well designed one. If you think this is nitpicking, I encourage you to (re)view the general sofware concepts of cohesion and coupling.

(Part of) gits success is it is a tool focused on doing one thing well - I believe Linus is on record as saying the other tooling (commercial/svn) largely failed because they were not really focused on source control i.e. patch management. Its part of the reason he constructed it in the first place, the tool he was using was overcomplex and bad at doing simple things.

Github's success until this point has been largely that it focused on building review infrastructure. It's based on git, giving it flexibility akin to being based on e.g. http, but it's core is review and facilities in support of that e.g. code search. It's a very particular type of review aimed at a specific audience, but it's not git, nor should it be.