Condescending feedback says more about the speaker than the listener. It is almost invariably about their own insecurity. This is true is almost all fields of endeavor, not just programming. Just a few examples of my own: Insecure bridge player: The queen of spades was a stupid play. What's wrong with you? Excellent bridge player: The queen of spades would have been a great play against a 4/2 split. But since you had…
I think it's because they are smart. Smart minds make a lot of internal noise, commenting loudly on every experience, making it harder for geeks to 'hear' their own finer feelings, including conscience. This makes them nervous, insecure and guilty. The guilt is unbearable, and they unconsciously attempt to project it onto other geeks with things like condescending feedback.
However, the good news is that there is a minority of geeks who have broken through this barrier, e.g. by meditation. They are a formidable sect, possessing both Bene Gesserit and Mentat powers.