i got confused because you said addresses. blacklisting addresses is imho the same as blacklisting coins.
blacklisting persons can only happen on exchanges (and its already done - see coinbase)
If you think coins can be blacklisted then you are very wrong. We already have mixers and if someone tries to "blacklist coins" there will be lots of services that will appear to help with that.
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That aside, regardless of where the deal is struck, be it on the forum or AOL instant messenger, GPG would still be used to sign the contract.
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You missed the main point. Sending money to MP means losing possession of those money and GPG will not stop MP to run away it them, while a smart contract will make it impossible for anyone to not fulfill the contract since the coins will be locked and will be released only when the contract conditions are met.
That's not real money. That 116 million exists only for the purpose of pretending to invest in derpy startups.
It's fake money? You are starting to be delusional. Those will not be invested in themselves and into mining equipment. You are very wrong about them! This is not HashFail who's dick is sucked by Icetard.