Yes this is a key point lost on many when I hear this argument. It doesn’t mean to not buy an EV, it’s still a great idea, we just need to do more work on our power sources
Within a decade from when my Volt was manufactured to when I sold it, the carbon emissions per kWh dropped from 500g/kWh to 372g/kWh. Gasoline emissions have not dropped and might even be getting worse as we have to reach further to get nonconventional oil from tar sands, etc.