"Pure capitalism represents voluntary interactions"

The "truly free market" can never achieve the "pure" capitalism you propose in practice, then, because deregulation involves a great deal of involuntary choices forced on the consumer (as opposed to being forced onto the business.)

And that's why you need regulation: it ensures that interactions are indeed voluntary, and that both parties have access to the same amount of information.

I agree, regulation is important. Too important to entrust to a monopolistic force on violence.