Your point of view here seems to neglect energy storage. There is no use for excess renewables that is more productive than storing it for later, when intermittent renewables go offline. Stored renewable energy is the only thing that can replace fossil energy at those times.

This is why billions of dollars are going into storage and transport for renewable energy (batteries, hydrogen, and some outliers like methane and ammonia). Creating any new energy demand, be it flexible or constant, only increases the total amount of renewables we need.

> our entire grid could be renewables in excess of peak demand

Are you hypothesizing about a world where we have more renewables than we can consume at all times? Sure, I guess mine away in that world. In this world, though, it's doing measurable damage.