Thank You...A Polite Gesture or Self-deameaning?

I have a question. I was just reading a critique of a query on a blog that I frequent and the agent said that you should not thank an agent for her time, because your time is as valuable as hers. I was wondering how people felt about that? Personally I think when you take time out of someone's day you should thank them. Regardless of those circumstances. I thank people at the store who check me out. I thank customer service people who I speak to on the phone. I don't think my time is one iota more important than theirs regardless of their position in the world. We're all on this planet for a very short time in the grand scheme of things and whether you're cleaning my carpet or delivering my baby the time that you spend helping me is that much time out of your life. You might only be doing it so you can feed your kids, or you may be doing it because you're just a nice, helpful person. I don't care why you're doing it. The end result is that you're helping me get the things done that I need done.

What do y'all think? Do you thank people?