I think the goal is to emulate Mastermind-style sessions, but online. CEO's of large corporate companies have participated in these types of round-table discuss

I think the goal is to emulate Mastermind-style sessions, but online. CEO's of large corporate companies have participated in these types of round-table discussions for years and (to the best of my knowledge) have genuinely benefited from these sort of sessions. I would be interested to know what you mean by a "community site" or a "single mailing list" in terms of how it would foster peer collaboration better.