It's a doubled sword. Sure you loss information, but others too... so way harder for a whale to try to manipulate the market. It is a really concept. I have not seen this done before. I would like to see how the market behaves when no one knows each other's hands.
Gox ran a dark pool. They're also very common in stock markets. Other crypto exchanges might well be running them too. They serve a purpose but it is a somewhat murky arena.