counterintuitive nipples
More fundamentally, I think people forget that source control is a very weird and very hard problem. Much like the lower levels of particle physics, you kind of have to implement the behaviour you expect using a model that's not intuitive. That the doc writers for git seem to revel in spewing nerdporn words like "tree-ish" at you is unfortunate, but people like seeing dmesg spew at boot for the same reason: it's obscure and therefore makes you feel cool.
Of course, no one needs to know how pretty much any vcs works under the skin on a daily basis, and that's why sensible git documentation exists. HELLO PEOPLE THE INTERNET HAS SEARCH NOW.