It's a fairly typical Unix tool, but: worse! It's got a rather cryptic and unhelpful command line UI that's often fiddly to use, rather requires you to understand its internals in order to work with it, and has lots of perplexing failure modes. There are GUIs for it, which do help, but people moan at you if you use them, and/because they're often opinionated and oriented towards some specific workflow or other. And they don't really stop it being fiddly to use, you still need to bear in mind how it works internally to use it, and the perplexing failure modes remain.

It's a generalisation, but, by and large, artists and designers don't enjoy using these sorts of tools. Also, they are more likely to be working with unmergeable files, something that git isn't really designed to work with.

(Programmers often don't like these sorts of tools either, but - again, a generalisation - they're harder to avoid if you're a programmer, so the average one is typically a bit more practised at putting up with this crap.)