More than likely it’s a cost issue, coal is artificially cheap thanks to several countries subsidizing the coal industry like Germany, USA and Australia.
There’s also I guess the practical question of how much plant fiber per ton of metallurgical coal is needed, i.e. how land would be dedicated towards ‘producing plant fiber’ for the steel industry.
In a just society all those people that force these workers to work those hours, wrecking their health like for example they’ll be exponentially more likely to suffer strokes and more severe ones at that, would be thrown in jail, holy shit what a misery that is put upon these people and for what? So some financial ghoul can shift some numbers from one pile to another and maybe buy a new jetski. It makes my blood boil how people are abused up for literally miniscule amounts of additional profit at this point, they are just grinding up the stone to get that last droplet of blood out of it.