The expected knowledge at LW...is probably middling to above average for me. More relevantly, much more knowledge of science, and in particular the sciences that contribute to rationality (or, more realistically, the ones touched on in the sequences), which tend to be fairly 'hard'. I've found a much higher knowledge of, e.g. history, classical philosophy, politics/political science, and other 'softer' disciplines is expected elsewhere.

I presume you are averaging over a high-sophistication sample of the internet, not the internet at large.