It's kind of irrelevant how much harm a single company does, since that company exists to serve a demand that would simply be filled by other companies if it didn't exist. Maybe those theoretical other companies would have marginally better business practices vis-a-vis the environment, but it's not like they would operate in a wholly alternative economic system.
simplifying down complex issues to fit "the curves" narrative often misses a lot of really important nuance.
to wit, let's imagine there's an incumbent company that serves out the demand in an incredibly efficient but environmentally harmful manner. further suppose this is a large national player that's willing to eat some losses in order to crowd out the whole "efficient allocation of resources" type new businesses that may spring up and serve that demand in an environmentally friendly manner.
according to "the curves", there's no room to displace that incumbent because they're stuck in a local maximum when it comes exclusively to satisfying demand. but it's pretty clear that there are externalities that, when considered, make it an attractive target for change by different players.
It's not irrelevant: a single company can undertake different economic activities that produce the same economic outputs with different ecological results. I've seen this first-hand in my line of work. When you make companies publish their greenhouse gas KPIs, they start to reduce them.
