PGP absolutely is decentralized - I can trust or distrust key X without communicating at all with any external PKI.
I agree that's not all that useful on a global scale - it essentially degrades to the current PKI setup then, because validating everything is expensive and doesn't need to be done by everyone every time to get nearly all of the benefit. But it is a significant difference for individuals making individual decisions.
I agree that's not all that useful on a global scale - it essentially degrades to the current PKI setup then, because validating everything is expensive and doesn't need to be done by everyone every time to get nearly all of the benefit. But it is a significant difference for individuals making individual decisions.