Batteries are just one means to store renewable energy and mechanical storage is another. Re-designing the power grid to transfer peak to areas via HVDC is another, to spread into areas where the weather limits or constricts the renewables for that time of day or day itself.
"Taming the Sun" [0] goes into more details and talks about it better than I can.
People like to over simplifying complexity by reducing arguments to a single reasoning. It helps make everything seem more simple than it really is. It is a way to persuade people that lack understanding "all systems are complex". Even instructions on how to construct a peanut butter and jelly sandwich. How many years does it take of development before a child can actually preform that "simple" task?
[0] https://mitpress.mit.edu/9780262537070/taming-the-sun/