[charlie0]

If they didn't moderate aggressively, they would probably end up with a bunch of duplicate questions. I really like the fact there's not a ton of dups on SO. ie, see other help sites. They also have a high standard for those questions, to the point where it will take 10+ minutes to post a good question. I don't ask questions either, mainly because I don't want to spend 30+ minutes writing a good question AND that's a good thing.

[hn_user82179]

IMO, the aggressive de-duplication of questions means that people will keep updating the answers as things change, which is really nice as you don't have to worry about the responses to a question becoming out-of-date/stale.

[eslaught]

I don't think people object to de-duping true duplicates. The problem is near duplicates, where the original question/answer didn't quite cover what you're asking. In those cases, it can be frustrating getting past the SO duplicate filter, which can sometimes be too aggressive.

Or, when searching for answers, you keep chasing your tail because the mods kept killing off the variants of the question you cared about, and you have to cobble together answers from the comments because those will often be all you get.

Or (and arguably worse), you'll find a relevant question but the answers are inundated with "like the real answer, but variation for situation X" because people are posting to the main question because they know the almost-but-actually-not dupes will all get closed out.

[IshKebab]

There still are a ton of duplicate questions. When questions get marked as duplicate they don't get merged or anything, they just lock the most recent ones (even if they are much better than the older one).

Their moderation doesn't prevent duplicate questions it just makes it more frustrating when the question you find has been marked as duplicate.