To be honest, I spend more time on HackerNews than I do on Facebook. I feel like I go to Facebook to see what people from Highschool and College are doing and to keep tabs on my local area, but if I want intellectual stimulation, it's too much work to dig through my newsfeed.

This isn't the first time this has happened; I remember when Reddit was small too (and if you go back on HN, the old HN had higher quality comments).

It's inevitable that the values of a community change as it scales. Different strokes for different folks I suppose.