> Because you get far higher ROI for the large-scale installations.

Right, but as always, ROI is hardly the most important thing in life, there is more considerations than just "makes more money". For example, as someone affected by a day long country-wide electricity outage where essentially the entire country was without electricity and internet for ~14 hours or something, decentralizing energy across the country seems much more important, than optimizing for the highest ROI.

But again, this is highly contextual and depends, I'm not as sure as you that there are absolute answers to these things.

Grid-tied solar is fragile. If the grid is not nearly-perfect, it won't generate. It will not help society as a whole.

If you personally have battery backup, that helps you personally and you should pay for it, just like you might pay extra to turn up the heat while I keep it lower to save money.

Grid-scale solar installations can be much more decentralized than nuclear or natural gas power plants.

Decentralizing through subsidies at the homeowner level is maybe not the best use of money.