I call this "nothing can ever happen for the first time". One often hears it in passive-aggressive arguments against renewable energy.
as my wife points out, we can't even imagine any of the things that do actually exist, only drastic simplifications thereof
This seems somewhat bad-faith: nuclear does supply the majority of France's power, and since nuclear is a "base load" part of the mix, it would be inefficient to get 100% of power from nuclear rather than a peaking-friendly mix that includes e.g. hydro and gas.