KYC is necessary because you do not want for money laundering to be easy. Nor sanctions avoiding, nor terrorist sponsoring.

KYC stands for Know Your Customer, the regulations that require institutions moving money between two parties to positively identify each of those two parties.

I think the intellectual position "it should be illegal for institutions transmitting money between two parties to identify either of those parties" might require some kind of logical argument behind it. Are you saying all financial transactions should be anonmyous by law? How would banks function if they were required to be blind to their customers? How would the government prosecute money laundering if all cash-trails went cold after the first time they passed a bank?

I understand people often like to express extreme positions on the Internet, but I think it's pretty easy to see an ideal society has rules somewhere in between "you're not allowed to know your customers" and "you can't accept a penny unless the giver does a blood draw in front of you and is confirmed to be in a central register of DNA".