But then you're not sorting based on quality at all. The idea is the best answer should be the one on top. That's not necessarily the most recent answer, but it's also not necessarily that one answer that is really outdated but has accumulated tons of votes by virtue of being around a long time either.
Active sort is still based on quality -- it's not strictly most recent, but some combination of recency and votes... maybe like Reddit's hot sort.
For instance, on this question I posted a nicely upvoted thorough answer to a popular old question whose other answers were dated. By active sort it becomes #2 (#1 is always the accepted answer), but by votes sort it's #4.
The part about an old answer that was highly upvoted but is no longer right definitely exists — I'm not sure if they've thought about solving that one.
