It is one of the central ideas behind bitcoin and leaves no doubt about the anonymity of the transactions.
It is a well publicised idea and it is even mentioned on the main page of the bitcoin wiki (http://bitcoin.it).
The reason people think Bitcoin is anonymous is because they think that identities cannot be linked to the addresses involved in the public transactions.
It is one of the central ideas behind bitcoin and leaves no doubt about the anonymity of the transactions.
It is a well publicised idea and it is even mentioned on the main page of the bitcoin wiki (http://bitcoin.it).