I think people agree with each other a lot more than we get or give credit for. We just tend to focus on what we disagree to on specifics while we let rest those things we agree to. Ironically, those agreable things just close off the conversation/thread and get buried as though it were less interesting or irrevant.
At least this is how I think we need to interpret the apparent lack of agreements with each other. It helps to hear it sometimes though, and thank you in return for saying so.
Those 'thanks' that some sites use can also act to bully others oddly enough, just as 'reputation' markers etc. So it helps to acknowledge others more like this.