It's not, grid-scale batteries are being deployed all over the world, and newer batteries keep getting better and cheaper. Storage hasn't been the issue for years.
To be fair, it depends if you were looking at "price/unit" or "sum of factory output".
The former, even a few years ago, I agree. The latter, people were arguing about a year or two ago. (Though your point remains as the trend was clear).
The former, even a few years ago, I agree. The latter, people were arguing about a year or two ago. (Though your point remains as the trend was clear).