Sure fossil fuel was necessary for some time but the only reason we kept going and still dependent on it despite the technological advancements and available alternatives is because of big corporations and some politicians who benefit from the industry (either financially or politically).

We could’ve stopped contributing to climate change some time ago but we choose not to. We can even do it today but we won’t. Change has been painstakingly way slower than necessary because some rich people decided it was not worth the effort.

It’s amazing what humans can achieve when we work together. We stopped using Chlorofluorocarbons and found viable alternatives when we decided it was worth the effort. We’ve eradicated smallpox ffs and we could’ve eradicated more diseases if we choose to.

That’s because in the fallout universe the nuclear war happened after electricity, and computers were a thing. I believe steampunk is an alternate timeline where technology advances without advancement in electrical and digital technologies (aka steam and hydro-mechanical energy). That’s a different setting from the nuclear power age of fallout.

I think the difference is based primarily on the main power source (steam, nuclear, or coal).

P.S. I’m not actually sure whether transistors exist or not in the fallout universe they might have existed but where a new underdeveloped technology.