I once answered a question on SO and included a link to some sample code (production-quality actually) that I had written several years before. The answer was (I thought) on-topic, clear, and helpful (it gave the questioner everything they needed to solve their problem). It was downvoted to oblivion, apparently because I included the link. Then I removed the link and just pasted the 150 lines or so of sample code directly into the answer, but my “reputation” is still negative as a result so I can’t answer any questions. As a result, I have zero interest in ever trying to contribute to SO again.