&gt; The chain wouldn&#x27;t contain any network of contacts (like GPG signatures) and only hashed information about the user.<p>If &#x27;hashed user information&#x27; means a function of the user&#x27;s identifier (e.g. the user&#x27;s email address, or some other global user ID), then privacy is lost because one could hash any user&#x27;s ID and see what his public keys are; many protocols include an identifier for the sender&#x27;s public key in order to guide the receiver, and vice-versa. This means that one could see what messages that user has sent or received.<p>If it doesn&#x27;t contain some function of the user&#x27;s identifier, then what would be stored exactly, and what would its utility be? If I can&#x27;t consult the global blockchain asking, &#x27;what is the key for smith@example.invalid?&#x27; then why have a global blockchain? If it&#x27;s simply a record where key X says key Y is the same as key X, then key Y says no it&#x27;s not, then key X says yes it is again … what&#x27;s the value?<p>Blockchains are an amazing innovation for achieving global agreement. Because of this, they can be used to bind easy-to-remember petnames (like &#x27;bill&#x27; or &#x27;Bill Gates&#x27;) securely, such that the entire world knows that BLOCKCHAIN(&#x27;Bill Gates&#x27;) is the founder of Microsoft, not his father or some random fellow.  If you&#x27;re not using a blockchain for global agreement, what&#x27;s the point?