While I strongly believe this is a Bad Idea(tm) of epic proportions with a list of unintended consequences that seemingly has no end, after my initial visceral reaction, I am left to wonder. What led anyone, or group of anyone's, to think this was the answer? Even assuming we are all Good People(tm), do they believe someone will report an incident just because they can do some anonymously? Okay, so we'll put their potential targets on notice but, the report isn't really actionable. The attacker will still be at large and free to prey on someone else.
Anonymous reporting simply seems to be the wrong direction. What about actually changing how we treat and support the victims?