> The gas plants could be 1% of given moment, yet still set price

Makes sense. Since no one would build that last 1% (or then, last 10%) of needed capacity due to it being wildly unprofitable. Then you are dealing with rolling blackouts or even worse.

The cost of a watt is not fungible. Reliable electricity is worth many multiples more than an unreliable grid no one can rely on being there when they need it.