KYC is stands for "Know Your Customer" and i think this is a system that identifies the true identity of a participants. And this KYC is important in order to validate cheaters and those scammers. But sometimes it can be used also by those scammers also by pretending to have a n ICO and will ask your information for their own benefit like using your information for bad intention and this is the disadvantage of KYC system implemented.
KYC (know your customers) can be cheated, KYC are required to know one investor where from.
But anyone can do KYC with fake identities, as many identification are stolen online, this is the risk on doing this system with some ICO.
If the ICO is a scam or even not we dont know if our documents are same with them or not.