If bitcoin were completely anonymous then how you gonna track scammers?
Humans have an inherent right to privacy. You can't erode that right. One day you are installing cameras on every car, and then in every home, and finally arresting people before they do anything wrong for expressing 'inappropriate attitudes'.
The answer to your question is: you don't. You solve crimes the hard way, but in doing so you ensure freedom and fundamental human rights. Privacy is coming, whether the world is ready for it or not. It's not a question of if we should - we are already doing it with Monero.
