Is there skill endorsement in Stack Exchange sites?
Have Stack Exchange sites considered skill endorsement for their users?
I can't speak for Stack Exchange, but I doubt it. In order for that endorsement to be in any way meaningful they'd need to completely change the way the sites work. The current badges for tags simply mean that you got X number of upvotes on answers for questions in that tag, but it doesn't necessarily mean your answers are good or that you actually know much about that topic; you could get no more than a single upvote on a large number of answers and still gain those badges.