I am very opposed to answers as comments.
Using the comments robs us of the ability to vote up or down or suggest edits, and basically defeats the functioning of the Stack Exchange engine. And since comments on the question go above real answers, it's a way to get in a first word, which is unfair to the real answers.
I've seen many people say "But, I did that because I didn't have a complete or real answer". That's actually worse! Now these lower-quality partial answers come above the real ones, can't be voted on properly, and can't be improved.
Answer-comments also push down comments which might be used to get clarification and improve the question itself, so they distract from the actual intended purpose of comments to questions.
If you have a good, succinct answer, please put it in the answer section. If you know that your comment is an incomplete answer, it's probably best to think about how to round it out. Or maybe just let someone else answer. Or, if you really can't resist, think about coming back later after someone else answers and deleting your comment so it doesn't distract. Maybe it could even fit as an edit to another answer, or a comment to an answer, which is less harmful since at least the answer comes first.
Some of this answer was lifted from my post over at Photo SE, Short answers as comments — please resist the urge