Effective vibrant communities are always multi-platform: there is no “on platform fits all”
They span interactions at different sizes with different channels: if one person or a small set of people have to be part of every interaction it’s not a community. Communities should foster one on one conversations, small groups, large groups, Special Interest Group or Birds of a Feather interactions, and some communications should be addressed to “everyone.”
Communities are about peers helping peers advance - self-organizing CoP model still valid.