There are tons of them with a lot of upvotes and comments but when you go in there's nothing but [removed] and [deleted] all over the place. It is very annoying to not being able to know if the question has actually been properly answered at all.
We most recently covered this six days ago. You can also search the sub for "answered" or "unanswered" to read many, many previous versions of the proposal.
tl;dr (because reddit loves those): No.
The mods are reluctant to say that there is a definitive answer. Many good threads have more than one excellent answer. There is often more to be said and they don't want a flair system that discourages further answers. Plus this might be hard to administer, as extensive and popular answers often turn out to be trash. I think I've reported a comment with over 1000 upvotes that was removed. So this modest proposal requires really extensive and immediate oversight of answers immediately to be relevant. Which would be awful to make the mods do when they already have time pressure to delete nonsense, and other things in their lives.
You likely will find this Roundtable to be of interest as we've addressed some of the issues with such a system there.