Most people aren't VCS nerds, most are of a generation that only ever knew git. Learning git was a prerequisite they engaged with out of necessity, not by choice, not after exploring the problem space and pondering about different approaches. Learning git was difficult, and the more they learned the more they discovered they had more to learn, including the little things, obscure details and a plethora of paper-cuts. For them (again, I suspect they are a majority), the perspective of learning something else comes with the expectation of a similar daunting effort and steep cognitive reluctance.

That's the paradox of git as I see it: had it been a simple and easy system to pick-up, it would probably have been replaced, and/or the VCS space would be much more competitive.