I don't think there is anyone I agree with everything on. If I found someone who fitted that bill, I'd be worried that only one of us was doing all the thinking.
It's my experience of web fora that it is far commoner to post dissent than assent even if one agrees with 90% of what others say. As for fitting in, I wouldn't expect to be chased off an overwhelmingly euroskeptic forum run by a confirmed euroskeptic just because my view on that issue differs any more than I would chase Christians or female arts graduates off the other forum I work on, just because they don't fit in with the majority inclination there.
When one agrees with something, there is as much point in saying so as in cheering from the back benches, to extend JMW's metaphor. When one disagrees and says so, there is at least an evens chance that either you will learn something or someone else will.