The comment above is a genuine addition to that line of thought; one which I'll maintain has substance and is worth reading.
I'll take your point on crossing into personal attack though. I definitely did call that guy ignorant of basic facts. However warranted I'll try harder to avoid that kind of talk.
Thanks re the latter point. I think the "however warranted" bit is significant (I usually put it this way: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...), because human bias is always to overestimate how "warranted" things are in one direction and underestimate it in the other direction. Objects in the mirror are closer than they appear, etc.