Coal

Actually, it's trying to understand historical dynamics.

It can come from charcoal too.

There might be things that coal can do which wood cannot, but steel is not one of them

Don't we only have coal because for a long time there was nothing capable of rotting and eating wood?

The supply of wood also matters. You need a lot of wood to replace a coal mine. Deforestation would have been a negative feedback.

You can still make steel, and places like Russia, Canada and South America have an almost endless supply of trees.

Not saying it would be ideal, not saying it wouldn't fuck up the environment, but it is possible.

Replacing coal with charcoal would not necessitate deforestation until you need more charcoal than you can grow trees. We'd have gotten some plantation policies running that would be unrecognizable to our world, but e.g. pine is cheap and grows real fast. It would obviously be more expensive if it was a primary fuel source, but it would still grow fast.