It can still happen. I've been actively using SO for 14 years and had my first question marked as a duplicate last week. The question was already 9 years old and had been thoroughly answered. Last week somebody decided to "optimize" it, which sent it to the review queue and finally led its closing.
It does seem likely that I'm an outlier . OTOH it could be that just people that have had bad experiences are posting their experiences and the silent majority without bad experiences aren't posting. It's so hard to tell in a forum format.
I think the loudest people are the ones talking about their bad experience. I've been on SO for, I think, 13 years. I've rarely had questions closed as duplicates and if one was it truly was a duplicate and I found my answer on the referenced question.
I don't see how all the people complaining about moderation don't look at all the low quality questions and see why moderation is what it is.
Personally I don't remember having gotten questions closed. However,
sometimes other people's good questions have gotten closed, making me annoyed that I didn't get to see any, or more, answers.