At some point no solution is perfect and anonymity brings its own set of issues.
What you are describing is also a cultural more than a framework issue.
People should not fear retribution for voicing their doubts and I'm lucky enough that none of my latest clients or previous employer had such an environment.
I built a pseudo anonymous forum system for a client. He would give out logins, so he could monitor behaviour and participation. It was used when two large UK charities merged. Be then produced a report based on the ideas that came from it. I don't know if he took the idea further.
What you are describing is also a cultural more than a framework issue.
People should not fear retribution for voicing their doubts and I'm lucky enough that none of my latest clients or previous employer had such an environment.