You’re not being pedantic, you’re just misunderstanding. Pumped hydro storage is not a dam, it’s not a power source, it is a power storage system. You can use pumped hydro at dams but basically anywhere you can move weight up high and use gravity to recoup that is a form of storage. It is one of the most efficient ways to store electrical energy with electric pumps and turbines. The point of a dam has been to collect water that is deposited there via rain and use that to create power.
So, back to our initial problem: chemical storage (batteries) is expensive, environmentally dubious, problematic in many aspects and inefficient, chemical conversion (e.g. hydrolysis) is wasteful/inefficient, etc. So, no, we have no good answer to that.
80% of this is just flat wrong. Chemical storage are not expensive at scale, enviromentally safe, not really problematic, and so outrageously efficient basically nothing comes close. Hydrolysis is more of a chemical reaction in organics and creating green hydrogen is done through electrolysis. It’s not wasteful or inefficient IF all of the power was surplus you had to get rid of because solar does that a lot. By your own statement solar panels are wasteful and inefficient because they only have efficiencies of what 22%?