"People don't realize how much information is out in the open."
That's Péter Szilágyi, an ethereum core developer who manages development on the ethereum software client Geth. He's referring to the fact that little attention has been paid to ethereum's underlying network layer, where information is exposed in complex, unpredictable ways.
Indeed, there's an awareness of the implications of such exposure that's given rise to an ongoing acceleration in research on how to better obscure user data at the application level, which sits on top of a fully transparent system that publishes smart contract and transaction data the blockchain itself.