I agree with how power is a bad way to measure batteries a lot of the time (though if you assume they last 4 hours you shouldn't be too far off).

But I don't think the residential line limits are too bad. A house that's sending out power takes its load off the grid and can also power multiple other houses without any lines being overloaded. And if an area has a high enough battery:house ratio, the full megawatt capacity of powering those houses but flowing the other way is a ton of power. (If the equipment can handle power flowing both ways.)