It's not a contradiction at all. Yes CEOs are the main beneficiary of the system but they're still accountable to shareholders who run on pure capitalism. There's plenty of examples of CEOs trying to do the right thing only to get sued by the shareholders then kicked out of their jobs. Nothing about corporations inherently needs to be done in a capitalist way, except the fact that publicly traded companies are legally required by law to run as capitalistically as possible, and if you don't accept Venture Capital or go public, good luck getting anywhere in this system.

Hell, basically the entire premise of syndicalism is to put workers in control of the workplace and let things naturally evolve from there. Once you remove the core pillar holding capitalism up, everything will fall down one by one like dominos. If you want to see a fraction of how that works just look at places with high unionization compared to ones without and it's like a completely different world.