I would say it was the other way around. It's easy to be against something, and it sets you above whatever you're criticising. It's much more difficult to sound smart while agreeing with something.
I discount the smart-soundingness of whatever I read accordingly.
ETA: Maybe that's one reason for this phenomenon: people trying to sound smart instead of trying to be smart.
I would say it was the other way around.
Agree. Intelligent sounding agreement that doesn't sound awkward is hard. I find it stretches the creativity far more and all else being equal leaves you sounding less impressive than the original speaker.
Link.
Given the positive reactions, I think the professor seeded them with a positive impression of the site's content.