In my experience, people who have technical discussions are often blind to their own emotions and the effect that their words have on the people around them. In good this can be solved. In bad cases, people talk about "discussing technical issues" and "directness" as a shield for their poor behavior.
An example from real life: A student, Y, was having a problem with her CS lab assignment, and talked to her professor, Prof. Z. She described what she had done and he said, "Well, that was stupid." In his mind this was just something that you say about bad code you've written. However, he was a professor, and he was saying this about a student's code, and he didn't think of the incredible negative impact that his statement made on his student.
In real life, this interaction took the "good path". They had a conversation, he apologized, and he changed how he spoke to students.
The "bad path" (which didn't happen) is where he justified/defended what he said or minimized/ignored the student's feeling.
Everyone comes to these decision points over and over again in their lives. It's inevitable. We all hurt other people. If we always defend our actions as being in the interest of "technical discussions" or state other reasons why our behavior is correct, is it likely that we are simply good people who never say bad things? Or is it likely that we are ignoring/justifying our poor behavior, and failing to learn and grow?