Another potential problem: If someone has asked a question that you know the answer to, but a user you're ignoring with this has written an answer. You won't know if what you're considering writing is just a duplicate of the already given answer, or if your potential answer contains something that might be of value to the asker (or someone else who comes across that question in the future.

Grove‭ Perhaps if that situation occurs, a little notice telling you something like "this question has been answered by a user you have blocked" when starting to write your own answer. That way, it's out of the way until it's actually useful.