Why do some people avoid to be involved with open-access discussions? Is there a link with individual personality profiles (e.g. people might be afraid to be judged in public)? Is open-access discussion facilitated with people you don't really know?
You mean, open access discussions such as in ResearchGate? Why should one be afraid of being judged in public? If someone is afraid of public judgement, then he should not be a member of such open access platforms.
The first group, those who just listen and read, should come forward to take part in talking and writing. Their views may actually be more acceptable than the views of the second group.