Couldn’t that same argument be used to justify stock market insider trading? The problem with insiders is not just that they can surface information, but they can actually manipulate the results. It’s why baseball players can’t bet on the results of their games, even if a prediction market guru might argue “their bets surface valuable information” or something.
That’s not the basis of insider trading in US securities law. US securities insider trading is premised on the idea that insiders are stealing from people they have an obligation to (the shareholders).