The way blocking is implemented on Facebook, once you block someone, you don't see their posts, and they can't see yours. In fact, neither of you can see any info about the other, not even posts someone else has quoted. You can unblock someone at any time, however. The problem with ignore on TBN is the ignored party continues to see your posts, which provides motivation for them to write responses, responses you won't see because you're ignoring them. This keeps an adversarial exchange alive, instead of shutting it down, as blocking does.