I'm not sure how this would work out with bans + comment moderation. I'd figure we wouldn't want to split up comments by tag and just have comments tied to the post. You can end up with a comment breaking rules of one community, but not another. Since you're following the rules of some communities, but breaking others, you might unknowingly rack up violations.

This might still be fine if we can ignore moderation from other communities, causing blocked posts to be visible again if we don't like a set of rules.