If we knew the COVID pandemic was coming, we could have prepared better. If we knew what AI would look like in 5 years, we could write laws for that proactively rather than reactively. The Fed could look at prediction markets to decide whether to raise the interest rate.

Basically, it depends on there being competent, good-willed people in power using them to inform their decisions. That feels like a bit of a joke right now, but things weren't always this way.