It takes a bit of getting used to but thank you, as well as greetings and signatures, really is just clutter. Of course it might have been different if we didn't have the voting system.
On a personal not, if you ever do feel compelled to post a thank you, please, please, please don't abbreviate it to thx or some other absurdity. I shudder ever time I see and makes me thing there are too many 13 year olds on the site.