Yeah, and part of the problem is that policy allows the bad boards to stick around so they multiply. In practice the bad policy means it doesn't matter how many good boards there are because there's a board next door hosting child porn or something.
It's the same reason why Reddit administrators hasn't deleted /r/the_donald yet, despite many of it's users breaking Reddit rules. It's hard to draw the line where it's acceptable to ban a whole community with "safe topic", because majority of posters are breaking the rules / law.