This isn’t true. It’s impossible to prove who owns what. Let’s say I have a transaction with one input and two outputs. Which one is mine? Both? Neither? Is one change? Only I know, and the person I’m transacting with.

Even if I send to an address straight from an exchange, how does one know it’s my address? What if I’m paying a friend (which I’ve done in this manner before)

KYC and chain surveillance is based on assumed probabilities. It breaks down entirely after a few laps around a circular economy.