Neither of those were concerns for US steel or standard oil breakups.
You don’t think global warming would happen regardless of oil being sold by a monopoly or not?
Big oil conglomerates spent a shitload of money pushing the global warming hoax hoax and it worked. Small mom-and-pop oil companies (if that could ever be a thing) wouldn't.
big tech on their way to speedrunning that too, with the AI data centre buildout