It’s because git is a complex tool to solve complex problems. If you’re one hacker working alone, RCS will do an acceptable job. As soon as you add a second hacker, things change and RCS will quickly show its limitations. FOSS version control went through CVS and SVN before finally arriving at git, and there are good reasons we made each of those transitions. For that matter, CVS and SVN had plenty of arcane stuff to fix weird scenarios, too, and in my subjective experience, git doesn’t pile on appreciably more.
Yes it is a complex tool that can solve complex problems, but me as a typical developer, I am not doing anything complex with it, and the CLI surface area that’s exposed to me is by and large nonsense and does not meet me where I’m at or with the commands or naming I would expect.
I mean NPM is also a complex tool, but the CLI surface area of NPM is “npm install”.