This might be because it's easier to write a quick putdown than a thoughtful comment, so the first comments tend to be the quick putdowns. Thankfully the more thoughtful comments rise to the top, but that takes time.
That's exactly the contrarian dynamic—your description is spot on! It's an artifact of the commenting process, not a representative sample of the community, and it happens in many threads. Maybe most threads.
https://hn.algolia.com/?dateRange=all&page=0&prefix=true&sor...