It is said that Bitcoin is anonymous and together with the dark-web it’s impossible to track the true identity of users and owners of these systems, this is not entirely true. There has been a number[1-3] of articles showing that bitcoin transactions only obscures your identity, similar to a e-mail address or an ip-address. To reach true anonymity you must take care of every fingerprint you leave on the net, every site you visit, every bitcoin address you use, every e-mail service and forum and always use VPN and TOR together. If you make one mistake someone has parts of your identity and this is the reason why both Silk road and Silk road II was put down by the FBI  and recently 400 darkweb sites was taken down .
The difference between privacy and anonymity is huge, in a democratic system privacy is key to let every one express it’s free will and vote on what they believe without risking punishment or manipulation, in a anonymous system there is no way to track cheating or regulate who has the right to vote. The same goes for bitcoin and is also the reason why bitcoin is a true democratic financial system, you cannot commit crime without risk, but you can do a financial transaction without being stopped or have your money freezed by banks just becuse they don’t like you .