There’s probably a significant element of consumer batteries being so good, so easy to setup, and so cheap to buy. That it actually ends up being more economical to take this approach, than build dedicated utility scale battery storage.

With consumer units, you can reasonably expect that they’ll operate with zero maintenance and zero direct supervision for a decade plus. If the cost of those units is low enough, that reduced operational burden starts looking very attractive, especially if you want to scale up your battery capacity across your network very quickly.