And the mechanism for appreciation on Stack Overflow is not thanks. It's +1 votes and selected answers. Those appreciate mechanisms drive the site and ensure the person who helped you helps many other people.
And there is no reason to remove that social lubrication because you're of a different opinion. If they're not doing the +1 and selected answer, then tell them to, but don't stop them from being decent human beings as well, even if you'd prefer the world that way.