This is a gross misrepresentation and compounded generally by misunderstanding of how corporate law works.
What is meant by this is "in most industries there are a small handful of companies that own some shares in a diverse array of other companies"... to say they "control" those companies, even if they owned 100% of it isnt fair either. Shareholders of other companies dont control them, they can vote for board seats, those board seats vote for CEOs, those CEOs have some degree of control. But even then they explicitly can not act in the interest of the controlling company, that would be illegal. They must act as independent entities and in fact **compete** with the parent company.