I certainly agree with your last sentence.

My own experience is that while people are more likely to express immediate disagreement than agreement in contexts where disagreement is expressed at all, they are also more likely to express disagreement with expressed disagreement in such forums, from which agreement can be inferred (much as I can infer your agreement with EY's behavior from your disagreement with Will_Newsome). The idea that they are more likely to keep quiet in general, or that people are more likely to anonymously downvote what they disagree with than upvote what they agree with, doesn't jive with my experience.

And in contexts where disagreement is not expressed, I find the Asch results align pretty well with my informal expectations of group behavior.