You often have the scenario where you post an answer and you realize it's not good, other people have already posted the answer (which you find out when you post) in which case your answer is just noise or someone comes after you and posts a better answer.
Also, technically you can "abuse" the delete process if you're above 10k+ rep. You just post 15 characters, delete it, edit it and then undelete it. This way you won't get downvoted for having a placeholder answer but can still get in first (timestamp wise).
IMHO deleting something within the first 20 minutes (or pick some other arbitrary time frame) after you post it should simply permanently delete it. Less noise that way.