It's certainly tricky to think about, when I start reading all the docs. (Someone just recently explained what "Pin projection" is to me, and I realized I hadn't really understood Pin before that.) But at the same time, it seems to mostly accomplish its goal of "you don't have to think about this in safe code." Is there a better way we could've solved the same problems?

I kind of feel the same way about Send and Sync. Like, why are there two thread safety traits? What could it possibly mean to be Sync but not Send? But at the end of the day, that's what's necessary to model the problem, and I've gotten used to it.