Right on. Some people will read it and it will have some sort of effect on those people. So I think it will help.

I have found old questions that have incorrect answers marked. If I am actively looking to solve a similar problem then the question is still valid and helpful to me. I might come back and post the real answer if I find it elsewhere. This is because I was routed here first by google so other people who end up in the same place will find the answer I found later without doing the additional research I did.

I think if the answer is reading the manual that it is unreasonable to expect someone to reproduce the content of the manual in a forum post. Linking to official documentation should be allowed with the note that the answer is already available, thus invalidating the question. Maybe the question should be downvoted after providing a link with a suggestion on how to learn more about the subject.