I can comprehend this sentiment, but, on the other hand, I rarely find "thank you" emails add anything to the conversation. It's just sitting there, wasting few seconds of my time to read it, distracts me when searching for information in old conversations with zero information added.

What's worse, "thank you" emails also socially force me to add mere "be nice boilerplate" to mu future emails to that person, instead being short and to the point. It's funny how technical, business, or fact based conversation can become unnecessary long and loose the focus with all that boilerplate.

On the other hand, being nice and polite is good in real life, on the face to face (or voice to voice) conversation, but, IMHO, just waste everyone time in email.