Also on Joel on Software: http://joelonsoftware.com/items/2015/01/20.html
Now this, my friends, is one of the major problems of stackoverflow today!
Again, though, you're missing the point. On StackOverflow, a stale answer can be fixed, by virtually anyone. On traditional vBulletin-style forums, the post saying "this isn't true anymore, there's a better way" might be buried hundreds of posts in.
I often land on a question that I'm asking, and it has a lot of upvotes, but it was answered 3 years ago using deprecated APIs.