They can but haven't.

Given this attitude, the answer to your other comment:

https://news.ycombinator.com/item?id=40511726 "As a junior employee, I have no patience for your point. Going into office is one thing juniors can do about the "problem with the culture" so my stance stays the same until the so-called culture changes. In my experience, the number of seniors who complain sbout RTO and don't hoard knowledge is tiny."

... is that it is likely that nobody is hoarding knowledge, they're just avoiding you because you're unpleasant.