Yes, but most of the traffic is from people going to the front page and seeing /all (this is what I read yesterday, I am assuming it is correct). My guess is most visitors who use Reddit's apps or go in through the browser are not participating in the blackout, or maybe don't care, so there will still be a large number of posts. The people supporting the blackout likely make up a large percentage of users who comment on new posts, and that is way down. I'm seeing a lot of posts, but far fewer comments on those posts.