These are very different because of the end goal. A world where we don't drive our food and eventually ourselves extinct is a world with vastly less gas use, to the point where the uses you highlighted (both electricity generation and home heating) are both eliminated entirely while I assure you we're not going to stop using water. We need to change how it's assigned, who gets access and to how much, but we're not going to eliminate it.

So then the question is, if we're eliminating all gas usage, why do A before B rather than B before A and the answer to that is very simple. Electricity is fungible, and it's much harder to change all the millions of individual home and small business installations, so you should begin with that first or you'll never get done.