How can they be legally blocked from ever taking a loss? It is a market. They bid.
There's a plethora of producers with varying equipment, startup times, ramp times, costs and so on.
As renewable penetration expands the most expensive, or least flexible ones are called in fewer and fewer hours until they shut down. If one oil and gas producer tries to raise prices a competitor steps in and fills the demand.
Did you think there was this one monopoly oil and gas power producing able to dictate prices at will?