If group of people who know each other reads a new website, because their professor told them so, and it seems like the professor dislikes the website... most people will write hasty criticism, because it is both SAFE and COOL. Only an exceptional meta-contrarian will write careful praise, because he has a different definition of COOL.
I'm not so sure about the label "exceptional meta-contrarian". I mean, I do this, but generally just because I disrespect my professors and enjoy getting in arguments with them if I think I can win. Does that count?
I am not qualified to answer this, because I do have no idea how dangerous your professors are or what are the possible consequences of disrespecting them. Or how socially dangerous is in your group to praise things that others criticize.
This is a general problem when speaking about real-life things -- many words (e.g. "dangerous" and "cool" in my comment) do have meaning, but at the same time they cover such a large spectrum of intensity that what you can say about one end of spectrum is often not true about the other end of spectrum. ...
Link.
Given the positive reactions, I think the professor seeded them with a positive impression of the site's content.