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.