I agree with you completely on the difficulty of getting clans together. I have experienced this, like you, when i organized the Red vs Blue some years back here on Sbrew. It takes lots of patience and listening and reasoning.
The challenge for a "Pure Community" Site is and always will be finding enough value to GIVE clans - where clans actually want to participate and do so accordingly. @Fake Smilebrings an interesting point up about the RAW list, which has been absent for years.
The previous community sites have for the most came up short (in my opinion) on establish enough value for clans - hence why they're dead.
Sharkbrew and the original PureCommunity forums have been the best we've had