In my experience, just adding politeness to a contrarian comment avoids the downvotes.

I had some downvoted comments but I think it never happened when I was politely disagreeing before making my point.

I think people (and I include myself) are more easily "triggerable" nowadays.

I also think we can fix this by taking the habit to write like we are attacking the point and not the person.

One easy way to do this is to overuse the "I" subject, even if it is to write and not just throw your facts. There is no real difference between « you are wrong because » and « I think you missed [that point] because » but the later is, automatically, more respectful.

This is a concern. In exploring any space we risk getting stuck at a local maximum. But this may occur when one holds on to their current ideas too strongly and immediately rejects ideas that go downhill so to speak. Flagging does seem overused on HN lately. It would be interesting to know many HN active users there have been over the years and perhaps that is the reason flagging occurs more frequently. For the record I have had various HN accounts for almost a decade and last month was the first time I was ever flagged.