I'm not so sure about that. Although Bitcoin is not anonymous, it is still pseudonymous. If you are looking at transactions, you don't know who exactly is behind an address and where those Bitcoins in that address came from. You don't know whether the money is from fraud or from legitimate business. And with mixing services and through other methods of anonymization like CoinJoin, it can make tracing Bitcoin extremely difficulty such that it is impossible to know who actually committed a crime and used Bitcoin to launder the money.
True. However, when it is time to convert from bitcoin back to fiat, problems will once again arise. It's at that point where the person cashing the coin would need to show the legitimacy of their income. If suddenly I were cashing out +10K USD, then alarms would be triggered and I would have to show where that income came from when asked.