A strike results when the opinions of a company's management differs from the opinions of the rank and file employees of a company. The employees go on strike in an attempt to get management to change their behavior. If the employees themselves controlled the company, then it logically follows that they will not need to strike in order to make the company behave differently, they need only change their own policies. But it always retains final authority and control over it. While I will not dispute that market power often results in political power, that is not the point being made.
Market power is the power to determine where resources are allocated.
While it is true that expanding the size of the cola market can help both companies, that is a different concern than the one in which, say, Pepsi is losing market share. The concentration of spending power means that resources allocated for the rest of the population are dropping in their share of the total amount of resources available. I am not arguing against centralized democracy, whatever that means As an aside, the amount of centralized democracy is what the writers of the American constitution had to grapple with. If it is the latter, I have not understood your argument. Stock prices reflect the first, because they often result in dividends for the financier.