I faced this in a community I managed. This was a community for experts and novices and we found that “experts” were more willing to respond with confidence, so any topic that was started would fairly quickly accumulate comments from this specific sub-group and not necessarily give space for new participants.
We tried creating topics that would encourage new, less expert, members to participate, but there was no way to stop the well-meaning experts from getting involved, so our less confident members continued to read, but not post.
We tried adding new members to a “hidden” group that showed them certain topics that were not visible to all members, but ultimately this was confusing.
We also had a similar experience when having a conversation about the differences in attitude to our subject between the genders. It seems the male members were still a little too willing to offer their advice (even if intended to be positive and constructive).
A means to (temporarily or in a focused way) limit the rate of participation of a group in target areas could be a useful feature.