So, questions remain open indefinitely then?

It helps improve the quality of answers given on this site. Some people will be able to see which answers have helped others a lot and take their cue from there to improve on how they can answer a question.

You can answer old questions, yes. Even if it won’t help the asker anymore, other people who search for it can still get their answers through old questions.

Questions don’t get locked if there are ‘too many answers’… just throwing that out there. Anyways, the reason is pretty much because those threads do have good answers it just gets to the point where sometimes people go crazy. The reason why they aren’t removed is someone may have the same question later on and instead of asking it, they can search and see answers. Just because a question is locked doesn’t make it unhelpful so it’s good to keep it up. If we deleted all those questions it would mess up the trafficking of the site, we don’t want that. Because trafficking is what brings new users to the site :)

Both great answers… cheers!