Oddly enough I think that is one of the reasons Git is popular: you are exposed early to a learnable mental model. (edit: it is a model of Git's storage interface, not a model of version control or a model of storage implementation)
Honestly, since when is that a great feature? I can't think of any other piece of modern software that requires that of its users (other dvcs with similar feature sets included). Noone should care about "internal" interfaces, no matter if they are easy to learn or not.
Programmers are pretty used to building mental models. And my point was that at least you can learn the git internals, but other "everything magic happens but we don't let you even reason how" source control systems are even less learnable than Git.