I might want a car with 300 miles charge for vacations, but most of the time be making trips to the grocery store. The grid might only dip into my car's battery for a 15-30 minutes at a time to prevent brown-outs while power plants spin up.
There are plenty of scenarios where the EV makes more sense than a dedicated battery for it.
Sure, if you have solar, by all means get a home battery and enroll it in the same grid backup program. Makes plenty of sense.
In my case, I live on a very shaded property; no solar for me. I also live next to an electrical substation, so extended outages from storms is highly unlikely; I'm first on the fixed list every time. In my case, the home battery doesn't make sense, but the EV might still.
EVs as grid storage is an option that may be compelling in some areas and for some people. I think that's worth exploring.
There are plenty of scenarios where the EV makes more sense than a dedicated battery for it.