[bowaggoner]

Prediction markets also exist for non-binary events, whether a finite set of outcomes, countably infinite, continuous, or beyond.

Instead, the problem is they still require an oracle for the actual event outcome. That is, everyone is betting on some event, but once it happens, an oracle is needed to tell the market what the actual outcome was. So they don't solve the oracle problem. They're another application that can make use of oracles.