I recently made a drastic edit to an accepted answer because it was wrong. The edit was rejected for the following reason:
This edit deviates from the original intent of the post. Even edits that must make drastic changes should strive to preserve the goals of the post's owner.
One of the suggested questions even discusses this topic,
If the answer is older, and maybe not likely to get engagement from the original author, you can opt to just edit the answer to make it correct. However, you run the risk of changing the answer's meaning. That path invites a possible revision war between you and the original author and/or community readers who disagree with the scope of your edits. So unless the edit is just making minor corrections (such as fixing typos, or easily-supportable technical fixes that are not opinion-based), I strongly do not recommend this route.
The suggested route is to downvote the answer and make a new one. I would argue that if there is an accepted answer to an old question with, in my particular case, 12 upvotes, a new answer is astronomically unlikely to usurp the accepted one. This policy of nonediting (and/or nonredacting) of incorrect accepted answers leads to the proliferation of misinformation without recourse from the community.
Why is the current policy the way it is? Are the moderators open to a policy change that will improve the information content of the site?