Grid scale storage is actively being worked on.
Chemical batteries, like rechargeable lithium ion batteries, are a big part of it. Sodium ion batteries and iron air batteries are coming up, as well.
Somewhat related are rechargeable fuel cells and flow batteries, that similarly store chemical energy that can support two-way charge/discharge cycles.
Gravity storage, like pumping water up into a reservoir and then using it to drive turbines on the way down, or elaborate elevator shaft type systems, can store some energy but require lots of land and material, or require very specific geographic features not commonly found.
Kinetic energy storage, turning lots of heavy flywheels and then recapturing that momentum to produce electricity when needed, is also on the grid (and kinda mimics the rotational inertia of the turbines traditionally synced across the grid).
Some other storage technologies include capacitors, pressurized gas containers, and thermal heat storage with molten salt that can be used to make steam to drive turbines on demand.
But all of these solutions are difficult to scale up to the point where they make a significant difference in addressing the mismatch between supply and demand at different times of day. We gotta do all of it, and right now the most cost effective solution is chemical batteries, so that’s been growing at an exponential rate.


It might be cheaper in some settings.
For certain food styles, I buy bulk spices sometimes because I don’t like to pay for an entire jar I won’t use, knowing that most of it will go stale by the time I’m through the jar. Being able to buy tiny quantities is sometimes way cheaper.
I’m also mismatched in my conditioner and shampoo remaining where I can buy the matching set and let the difference persist, or I can try to buy a single catch-up bottle of whatever I have excess of, to hope that they even out by the time I get to the bottom of a bottle.
Basically, I can imagine where it might be preferable (for both cost and convenience) to buy an arbitrary amount of something rather than buy a fixed factory container of that thing. I know I already do it for certain things.