I don't know about coinbase for selling KYC but i think KYC invented to catch illegal person who doing fraud to another. On the other hand exchanger using KYC that may be government rules of that country as per money londering case. But finally i believe that if you want to bounty or trade or business in crypto currency and if they need KYC you have to pass. Otherwise you are not able to work. So you think what you will do.