I was extremely active on SO and other SE sites in the late 00s and early 10s. In those days it wasn't too bad, many duplicates were actually duplicates. However that really did start shifting. This is anecdata of course, but even questions that linked to possibel "duplicates" and pre-expalined why it wasn't the same question were often just closed as duplicates of the exact question that was linked. This happened to me several times before I got fed up and moved on with my life.

SO was a really rewarding place to ask and answer questions in those early days. It really is a crying shame what they did to the community by empowering the worst of the community to be the bosses.