1) Is there another company that benefited from that missed opportunity? No. K8S is free and it "makes money" in the sense that it's a great on-ramp for GCP, and therefore GCP is happy to subsidize it.
2) It's never too easy to be the "first" company to break into a new technology or opportunity. Look at Altavista, and how it lost to Google in just a few years, despite when Google started Altavista was already a huge company.
3) I am not sure that your proposed solution would have worked, at least in terms of making Docker successful. It is the obvious alternative, but hard to be certain that its outcome would have been a better one for Docker (the company).