You are correct in a harm reduction and progress sense. Unfortunately harm reduction and general progress were something we could have spent the 200X's or 201X's doing. The remaining carbon budget does not afford for such marginal optimization anymore. We need to reduce total vehicle-miles-traveled by something like 50 maybe even 80%, while making those remaining miles EV/ZEV driven with 90 to 99% less co2 per mile.

So yes, even powered by a coal plant, EVs are better than cars. But no longer better-enough for that to be ok on its own. It is more important to figure out ways to de-car lifestyles than it is to foster EV adoption. They're both important, just de-car'ing is more.