Your question is irrelevant to my main point: that you're making a huge, unwarranted assumption that people who don't reply are necessarily ungrateful.

As someone who has rejected people in the past and has told people why they were rejected, I have never expected nor felt in any way entitled to receive a response. I have told them why I have decided not to hire them. Some people thank me for the critique. Others do not. It doesn't matter and I certainly don't make the huge logical leap of assuming that those who don't reply dislike me personally.

I think you misunderstand. I am not assuming they are bad people who have bad opinions of me (obviously, I can't tell). Rather, I am taking a conservative position about whether I have offended them: I suspect I have, and its better not to do that.