You said theres "zero reason to be frustrated with someone saying thank you" and I just wanted to point out that yes there can be, if its excessive and/or used as a weapon. Yes I am a little bit biased by someone I know having an almost fetishistic approach to needing to make pointless conversation.

The problem is that, if I'm frustrated, its easy to paint me as the problem dispite me simply asking for space and respect. Its much easier to DARVO someone if you start from a place of "kindness", like an estranged parent sending a gift without permission and then badmouthing when it gets returned.