This also assumes the same pot of money is being used for all kinds of energy generation, which is not always the case because bureaucracy. Also also pretty much all renewables are intermittent besides hydro which is not available everywhere. It might be more expensive, but both having diverse energy sources and baseline power is good for the grid. Wind and solar also do not provide any grid Inertia,, which is important for maintain frequency. I wanna say it was Ireland (feel free to check where) that actually had too few conventional generators and too much wind, and they had to build basically just a massive flywheel to regulate their grid