That's the primary factor which would determine the outcome. As a community, you probably want to attract currently undervalued people and help them to uncover their potential. If it's just invite-only community, I expect it to stagnate and never reinvent itself for the better.

There are a few good public forums (like lobste.rs) which require invitation to comment, and I inevitably end up ignoring them after I want to contribute to the conversation and realize it's not possible.