I routinely delete one-line answers that are more like throw-away comments. I do leave a comment explaining why, but I don't usually give them a warning because it means I have to check back later if they actually improved the answer. I always assumed that if the user wanted to have a chance at answering the question properly the user could just submit a new answer.
Is that actually possible? Or is there a system block that will prevent a user from answering a question after one of their answers on it was deleted by a moderator or the community?
I just realised I don't know for sure and can't seem to find any mention of potential blocks, apart from the one preventing them from undeleting their original post.