You are absolutely correct, although the point still stands in the context of the discussion. They aren't making money from accepting money in exchange for GPL software (people can just grab CentOS if that's all they want), they're making money from support, services, and non-GPL software that gets bundled along with a bunch of GPL software.

The discussion is about whether someone could run a business that is every bit as financially successful as a business that sells proprietary software, by asking for money for GPL software, and not having any other sources of income. Some posters seem to think this is feasible; I would disagree.