I think there is another example of the wrong answer getting highly upvoted (& accepted) in this question, which got on to the hot network questions (HNQ).
I made a meta stack exchange post about it to seek advice because I've exhausted the normal routine. At the end of the day, the post does not answer the question. It got massively upvoted because it is, nonetheless, an interesting post (it deals with a different question, see my comments on the post). I believe it got upvoted so much because of being posted quickly on a HNQ, and suffered from voting bias (people see it is upvoted, assume that means it must be a good answer, and add an upvote themselves). The post is interesting, hence it gathered some upvotes, but if one actually critiques the answer, they would conclude it does not answer the question.
There is a normal routine to follow for bad answers:
- Downvote and comment (request improvements, highlight the problems)
- Post an alternative answer
However, as a community I believe we should be going one step further - flagging or deleting such posts. This is because (as demonstrated by the post that I have highlighted) downvotes and comments can be ignored, and it is unlikely to "overtake" highly upvoted answers by posting an alternative later on.
Personally I feel that if the post fails to address the question which is being asked, then the user has not attempted to answer. I'd say this qualifies for flagging as not an answer: while the post may be interesting, it is not a relevant answer for the post and should be removed by the mods.
Likewise, if we are allowed access to delete votes (>10k rep?), then we should be voting to delete.
Another alternative is to post the question the user does answer and ask them to transfer their answer, but I don't think this a good alternative - the user who posted the answer is unlikely to be tempted to delete their big rep earning answer.