Maybe someday someone clever will figure out how to disseminate that knowledge, but it simply isn't there yet.

Based on Razib Khan's blog posts, many cutting edge researchers seem to be pretty active on Twitter where they can talk about their own stuff and keep up on what their colleagues are up to. Grad students on social media will probably respond to someone asking about their subfield if it looks like they know their basics and may be up to something interesting.

The tiny bandwidth is of course a problem. "Professor Z has probably proven math lemma A" fits in a tweet, instruction on lab work rituals not so much.

Clever people who don't want to pay for plane tickets and tuition might be pretty resourceful though, once they figure out they want to talk with each other to learn what they need to know.