My biggest issue with SO was that all the answers were outdated. In the beginning, if you found an answer on SO it'd be still relevant because SO was relatively new. But then as it got older, so did the answers to questions.

The ridiculously strict "no duplicates" policy guaranteed that the old, increasingly outdated answers would remain the only answers forever. In retrospect, I believe a site like SO wants to encourage some rate of duplicates, to ensure that answers remain fresh.

Just yesterday I looked something up on SO and the answer was 14 years old. Would've been a pretty relevant answer back when I first started using SO, but not now.

They really killed themselves through strict moderation. It's incredibly sad, it was a good resource while it lasted.