I've seen there's something about giving and receiving advice that seem to touch off primitive and core emotions. Advice receiving is the largest cause of contention in my real life relationships. I can only speculate the reason for the other person's hysteria: the mother/child metaphor, a need to be needed, establishing seniority, or a shattered self-image of being kind and sage. It also feels that "critics" are the most reactive when someone criticizes them.

I agree with ididitmyway's point that delivery is all important. I think a little thing like a pronoun can make the difference between seeming superior, talking to someone as if they're stupid (or reminding them of kindergarten) or imparting an opinion in a uncondescending, neutral way.