Understanding "anonymous transaction" I have read 


  In the original Satoshi whitepaper, it was recommended that Bitcoin
  users use a new address for each transaction to avoid the transactions
  being linked to a common owner.


But in reality, when A buys a bitcoin from B, A sends money to B to B's account in an exchange (or whatever account.) It seems that B can be identified via this dollar transaction by an exchange or the authority?
The original Satoshi client (now called Bitcoin Core) was developed from the whitepaper. Exchanges, online hosted wallets and many other things requiring identification came later. You can still run Bitcoin Core or a similar wallet on your desktop and many people value the anonymity.

You are right that when you use an exchange or another service where you are required to identify yourself, link bank accounts or, other similar activities you can be identified.