That's great for regions with hydroelectricity, but the significant majority of the world is not lucky enough to have that geography. Also, the places that do have good geography for hydroelectric storage also usually generate their electricity from dams anyway and thus don't benefit from storage.

Well when you find a region witout hydro or interconnects or sufficient renewable resource that neither are necessary to exceed 75% penetration just by adding variable loads then let us know and we can put the chemical batteries there first.

Most of the USA, for one. Some states like mine are fortunate enough to have 70%+ hydroelectric generation. But in aggregate, the country creates 6% of it's electricity through hydropower. If our plan is to use hydro when wind and solar aren't producing we're very limited in terms of renewable production. The US uses about 12,000 GWh of electricity per day. The entire world produces about 500 GWh of batteries per year and this price is climbing as lithium shortages impact the supply chain. Batteries aren't going to cut it. That's why plans for a renewable grid either comes with either plans for extensive blackouts or some silver bullet solving storage.

Again, "variable loads" is a pretty euphemism for "shut off the power". If we're going to be shutting off power to industries the cost of reduced economic output needs to be counted.

So a country with a lot of existing interconnects and hydro where a complete renewable transition would cost less than nuclear and very barely more than the cheapest fossil fuels is your example?

https://www.sciencedirect.com/sdfe/reader/pii/S2542435121002...

And pretending adding off peak EV charging to carparks or building hybrid renewable+electrolyser stations that provide all their own energy needs and export during high demand is the same as shutting off existing critical infrastructure is laughably dishonest.