I just tested the post quality filter in the answer area, and entering nonsense text like "qwerty" repeatedly did not trip the filter. Why?
Based on what I see in the flag queue, answers do not have a low-quality filter. Or, if they do, the bar is very low.
It is much easier for mods to dispose of bad answers than bad questions, and users who post too many bad answers can be answer-banned.
Yes, you get a message like "The answer you posted is too short" when you post a very short answer.