"Q: Why do you need a native token?
A: SelfKey will require participants to stake a certain amount of KEY tokens to access the network. This prevents spam, decreases the total amount of float, and encourages people to buy and hold KEY, and act in accordance with the trust framework (legal agreement) so that relying parties dont for instance, misuse identity data because if they do, they will lose their stake. Identity owners will need to hold a certain amount of KEY to unlock marketplaces also. We call this, proof of reputational stake and bonded notaries."
This is quite clever I have to admit