"If it were that simple to run a grid on 90+% renewable energy then I would expect some nation would have made it work by now. "
Norway, Iceland, Paraguay, Costa Rica, Albania, Ethiopia, and Bhutan all do exactly this, you numpty.
As for the idea that more renewables means more blackouts, I think you'll find that the US suffers a shit ton more blackouts than European countries that have pushed hard on renewables. Here in the UK, I have *never* experienced a blackout or brownout. And UK electricity pricing for consumers is set by gas marginal pricing, and this would have been true whether we had moved to renewables or not, because .... that's the fucking point of how marginal pricing systems work. Whichi s why we're delinking it now. (And anyway, US electricity prices have shot up in the last year, as your failure to invest in your grid is coming to bite you, and this is a story that's nowhere near finished, and is getting oil shock coming on top of it, too, so enjoy it all)
Also: imagine being on a tech site, yet unable to grasp the idea that technology improves over time, despite that exact thing happening extremely rapidly for both solar and wind, as well as BESS. What a numpty.