First, out of several games, I think I've only once been matched with someone who has set any banned or disliked cards (unless their lists were exactly the same as mine which I doubt).
Second, I highly doubt that that many people have lists which are similar enough to actually keep you from playing certain cards (unless you play the same opponent(s) over and over).
I am very grateful for this feature. This is one of the features I've been wanting. If you get matched with me, we'll play a fun game. Without this feature, if you got matched with me and one of my most hated cards was on the board, I would probably resign turn 1 anyway. What's the fun in that?