It’s always economics.

There’s a joke I’ve heard that says something like anybody can build a bridge that stands, but it takes an engineer to build one that just barely stands (i.e., one where the materials and labor actually cost money).

That also reminds me of my first router - it was my PC. 10x the cost and 1/10 the features of a purpose built router, but I already had the computer and just needed to provide internet to 1 or 2 more via Ethernet.

Likewise, it’s easy to design energy storage concepts of all kinds. It’s a lot more tricky if you want it to be economically viable and see mass adoption.