Everybody has a copy of the blockchain?
So? You still don't know which accounts belong to whom, and sometimes you don't even know things like which part is the change and which is payment.
Pretty far from "perfect information".
No. Who's paid whom is not the monetary system. Monetary systems are typically primarily defined by the money creation and distribution properties, which ARE *perfectly* known in bitcoin. Other systems may purport to offer near perfect information (eq, a gov that says "we will never devalue our currency"), but obviously such declarations are not credible. Even the gold standard had an imprecision component in that it can't be known how much is going to be "discovered" or "mined" in any given future timeframe.
To be more clear for those who may not correctly intuit the term "monetary system":
Bitcoin is the first monetary system to credibly offer perfect money-supply dynamics information to all participants.