It's kind of like asking whether the vital piece of a table is the tabletop or the legs, when you don't have a functional table without either one. We don't have a functional market system without supply and demand.

In a weird way, blaming the corporations is philosophically aligned with supply-side dogma, where the corporations ("job creators") have an intrinsic motivation to produce. As if they just churn stuff out all day long, because that's what they do when the government doesn't get in their way, and it's the duty of people to consume so the output doesn't all just pile up in some great heap outside the factory.

There's a reason some call that "voodoo economics." Whatever their influence today, all corporations producing things evolved in a symbiotic relationship with consumer demand. We could guillotine all of the CEOs, and revoke every corporate charter, but it'd do jack for the environment, unless unless we also all change our lifestyle.

Blaming the corporations makes as much sense as them blaming us. It's time to move past who's to blame, and instead start fixing things.