Converting electricity into heat and then back into electricity is a lossy process that is constrained by the second law of thermodynamics. Basically generating heat is easy and efficient. But converting it back to electricity is typically less than 50% efficient. Basically, it's several energy conversions in one process: you use electricity to produce heat, heat to produce mechanical energy, and then mechanical energy to produce electricity. All of those steps are lossy, some more than others. And it multiplies. It adds up to less than 50% efficiency, at best.
Lithium ion batteries are much better at over 90% efficiency. But they are relatively expensive for large amounts of storage. So they don't scale. But they have no moving parts and you can scale the capacity at which they absorb and release energy pretty much linearly. Which is why they are popular for balancing the grid.
Pumped hydro, which is a type of battery that has a relatively large amount of deployed capacity in some countries (many gwh of power stored) is both efficient and cost effective. But it's highly dependent on terrain. Yet parts of Canada run almost exclusively on hydro and pumped hydro.