Tbf it's a normal problem to have, it wasn't meant to be a forum. But it looks like they haven't considered what to do with the moving parts of the community once they reached content saturation. 😄
It’s also a problem for advertisement revenue and therefore funding. If there is an active discouragement of any interaction because questions are simply closed as previously answered, then page views fall dramatically, and revenue with it. You only need to load a page once if the question and answer are already locked.
Isn't it a good thing if your question is marked as a duplicate? That means you now have lots of answers readily available which already answered the question.
Often the question marked as a duplicate isn't a duplicate, just the person marking it as such didn't spend the time to properly understand the question and realise how it differs. I also see lots of answers to questions mis-understanding the question or trying to force the person asking down their own particular preference, and get tons of votes whilst doing it.
Don't get me wrong, some questions are definitely useful - and some go above-and-beyond - but on average the quality isn't great these days and hasn't been for a while.
Not really. A question that’s simply closed as a duplicate isn’t going to get any answers, and the answers to the original question, while they may have once been reasonable enough to be accepted, might be outdated.
Languages move on and add features, and closing any question as a duplicate precludes new, modern features that provides a better way to answer the original question.
A lot of content on SO is dated to say the least, precisely because reputation harvesters with a dated knowledge of the language are overly keen on closing questions.