There is certainly a bias towards long positions due to these dynamics, but wouldn’t you expect this to be at least reflected in derivative markets? The way I understand it is, if there was such a simple correlation, someone smarter and more equipped than me would already be betting on it at enough scale for the information to be integrated into prices.

If you can reliably make accurate predictions, then why on earth would you be talking about it instead of making the correspond bet via some combination of securities?