Board Thread:Support Requests - Community Management/@comment-6125731-20170720232605/@comment-24055022-20170721010528

Yep. You just use the regular block. And that applies to the entire wiki. You cannot just block them from Discussions.

If users only use Discussions and not the actual wiki, it would be best to warn them of their misbehavior on the post that they're misbehaving on, because they'll most likely never get the message on their Talk Page/Message Wall, especially if they don't have their email confirmed and notifications enabled, which most only-Discussions users don't.