"Even without a power structure, people will try to dominate, bully others, by posting more frequently than anyone else in an effort to drown out other opinions or contributions."
This can be easily countered with setting user quota (per day of week or whatever) on emails to the list. Not that this is a cure for all - but I believe this can improve the democracy of mailing lists. I hope some mailing list management software will add this as an option some day.
Some of the Wikipedia mailing lists did this a year or two ago, adding a limit of 30 posts per person per month. Not sure it's had any significant impact on the community, but it has somewhat reduced the volume of a few really, really prolific posters, which is a slight improvement to the S:N ratio. (There exist mailing lists where the most prolific posters are also good contributors, but imo this is not true of the Wikipedia lists, so the cap has mostly excluded posts I find noisy/redundant.)
You combine a power structure (control over others in some respect) with pseudonymity and you'll accelerate this problem. Even without a power structure, people will try to dominate, bully others, by posting more frequently than anyone else in an effort to drown out other opinions or contributions. The anonymity disinhibits this behavior further (called the "greater internet fuckwad theory"): https://en.wikipedia.org/wiki/Online_disinhibition_effect