Neither cursing nor thanking LLMs is useful. Relating in emotive syntax puts you in the wrong headspace to get the most out of the chat.
We anthropomorphise things very easily -- dogs, toys, cars -- because we're wired as social beings to have theory of mind. It's no surprise that AI chat, which mimics us, is popular.
Dogs are social beings and have minds. They understand cursing and thanking. Maybe not the actual words, but certainly the emotion behind them.