Understand that only ~6 TWh of lithium batteries have been produced to date. As in, every single year of production combined adds up to less than 6 Twh. Moore's law largely stemmed from the fact that making a processer faster also meant making transistors smaller. Reducing the width of a transistor to a half, a quarter, etc. increased compute per cm^2 by double, quadruple, etc. Chemistry doesn't obtain that kind of exponential growth - we have hard limits on the number of joules we can store per gram of anode and cathode, so scaling up production means digging up more anode and cathode material out of the ground. The nature of resource extraction is that the easiest-to-exploit reserves are exhausted first, and continued production is contingent on accessing the progressively more and more inconvenient reserves. Maybe in 2030 annual global production will be 30 TWh - we'll know in 4 years. But there's a lot of people who probably don't want to make trillion-dollar investments gambling on that possibility panning out.

Regardless of your confidence in battery production's continued growth, I think you'd agree that if someone is making a calculation about the required amount of overproduction required to maintain a stable grid, they should at least mention that their calculation is contingent on provisioning tens of terawatt hours worth of grid storage.