this seems simple, but they avoided an obvious data point: how much do solar owners earn by selling back to the grid, and how much do consumers of that energy pay for it?

It's a blip. A couple of years of battery deployment and people will be incentivised to different patterns and supply pricing will settle down. Making VPP (virtual power plants) and starting to leverage Vehicle to Grid will help as will scale BESS and pumped hydro.

This too will pass.