That's what makes the insider trading argument so tantalizing--it's arguing that it helps move the market closer to perfect information. But, of course, the world is complicated and dynamic, and it tacitly depends on all kinds of assumptions and beliefs about the resulting costs and benefits. It would be nice if the debate shifted to pinning down those assumptions, quantifying them as best as possible, and then iteratively tweaking and adjusting regulatory models. But that's true of just about everything and probably too unrealistic an ask, especially at a time when one side is convinced markets are just a mechanism for unjust exploitation, and the other side is convinced regulation is what sustains inequity (to the extent inequity is something even worth caring about).