But if a coordinator doesn't accumulate enough liquidity, then like you posted, it would be less secure, inefficient, and therefore a less effective way to CoinJoin outputs.
Yes, bigger coinjoins are more efficient than smaller coinjoins.
That's probably why the "reputation" of the coordinator matters, especially if the individual who bootstrapped it is an anonymous. But it would probably help if he/she is a known entity in the community.
Plus, I know the liquidity pool is supposed to be made of user inputs, but if not many users actually want to use the coordinator, then there should probably be a bootstrapping process during the start, no?
The coordinator can participate in their own coinjoins of course, but they still only count as 1 user.
Quick question, what if the entity that started the coordinator started bootstrapping it by using different wallets, pretending they're owned by different individuals, but with honest intentions?