KYC does matter for social platform like Facebook? They know much more about you than any 1-2 KYC documents. You post status and pics there with all location you travelled. Even eating habits and what you like or not. So dont worry about privacy with FB because there is no privacy there 
I agree, actually we unconsciously give our data to them. Starting from who you are or your parents, also the telephone number for the security of your account. In the internet era, privacy is not new unless we are not connected to the internet