The basic unit of analysis in think tanks and media is nameplate capacity, ie a MW of four-hour battery would be compared to a MW of gas turbines.

The most important driver of power system costs is "firm capacity"; a MW of four-hour battery might be 10%-50% as valuable as a MW of gas turbines given that the latter will run for 100-1000 hours per year when the batteries are empty and the prices are much higher. This is true on the grid or behind the meter.

The word peaker left out of the title makes your complaint meaningless.