How would this work though? You have 4m worth of blacklisted bitcoins. What happens if you go to a legitimate store, like NameCheap, and buy a domain using those bitcoins. You're going to add NameCheap to the blacklist now, because these coins went through them?
Well, you could say NameCheap wouldn't accept those coins in the first place, but can you really expect every store and person to be using this list?
What happens if you take those 4m worth of bitcoins, send 3m to your own wallets, and distribute 1m to random wallets of strangers? How do you know which wallets to blacklist? All of them? You're just going to put tens of thousands of people in the dark, and say their bitcoins are now worthless and blacklisted, because they received a random payment?
Well, you could say NameCheap wouldn't accept those coins in the first place, but can you really expect every store and person to be using this list?
What happens if you take those 4m worth of bitcoins, send 3m to your own wallets, and distribute 1m to random wallets of strangers? How do you know which wallets to blacklist? All of them? You're just going to put tens of thousands of people in the dark, and say their bitcoins are now worthless and blacklisted, because they received a random payment?