When someone with a PhD in the relevant field, 6 or 7 years of professional programming experience and several successfully shipped products under his belt starts learning something new, he's a junior at that new thing.
My point is that knowing all of a languages features is neither necessary nor sufficient for getting real work done even at the highest level. I've worked with some pretty smart and experienced people in my career and non of them would probably claim to know every single obscure corner of their favorite language.