I don't think that's quite the case. For a simple example you can consider a developing area without an electric grid, where people individually or on a communi

I don't think that's quite the case. For a simple example you can consider a developing area without an electric grid, where people individually or on a community level burn fossil fuels to provide lighting and heat, power schools and medical facilities. This use is fundamentally different from an industrialized nation that has a fully powered electric grid and alternative means to power it, but uses fossil fuel out of price or convenience considerations. Yes, it's rarely this clear-cut in reality, life and economics are complicated, etc. Still though, it's clear to me that not all fossil fuel use is ethically the same, and people still using fossil fuels can indeed have valid moral positions against others using them.