I would say that voting is a rough measure of (perceived) helpfulness.
All other things being equal, a "fast" answer is considered more helpful than a "slow" or "delayed" answer. Unfortunately that is true (on this site) even if the slower, longer more thoughtful answer is objectively better than the fast answer. To paraphrase General George Patton, a mediocre attack today is more useful than a brilliant attack a week from today."
I, (and probably others), upvote answers based on their usefulness to me. I can't judge the best answer (in math, anyway) from its value to experts. The best proxy is its value to me. So a simple answer that seems to "make sense" could possibly be more "helpful" than a long, detailed, "airtight" answer.
I do give a lot more thought to downvoting. I won't downvote on "mere suspicion" but only when I am sure that something is (seriously) wrong.