I think you are assuming that turbines would be paired with a certain number of batteries and taken together that would provide continuous power. But that is just not how a grid works or how the economics work. Battery storage is economical because you can buy cheap and sell high. And a system with high renewables penetration will see some very high prices for a few hours or days per month and cheap prices the rest of the time. That is ideal for battery storage, particularly as renewables gets cheaper.