> ...not every maintainer uses git.

I can't think of a valid reason for people to avoid learning git. Is there one?

"Avoid learning" and "not using (for this particular job)" are different things.

Is there a valid reason to move to git from any other VCS a person happy with, regarding time and resources one have to spend on it instead of productive work?

It could be beneficial for a Linux distribution sticking to only one tool to be able to build a common Workflow around it. For example Debian only uses one bug tracking system which might not be what everyone likes most but imagine what a nightmare it would be if everyone would set up their own solution for their package.

I can't contrast git with all the different VCS tools that are available, but different tools have different capabilities with respect to working offline and reconciling branches.

At any rate, it was an honest question. I'm not familiar with any salient reasons to not use git. If the only reason is that some developers still haven't learned git yet, I guess that's an answer. Not a very satisfying one to me, but it's worth knowing that's the reason.

There are those of us who have learned git and still prefer Mercurial. It's really annoying that git is supposed to be what we use across all programs, distributions, operating systems and hardware. Just about ASCII or TCP/IP are the only things that are about as universal, and git shouldn't be nowhere nearly as foundational as them. There should be room for more than one way to do source control.

Sadly, mercurial-buildpackage in Debian is a dead-end. :-(