Monopoly power on the producer side

I didn't know how to frame this title but still want to capture my thoughts about recent changes we see in monopolistic behaviour. The govt has usually looked at the monopolies in industries serving the consumers and they use a HHI index to assess the competitiveness of an industry and approve/disapprove mergers based on the projected HHI index after the merger. Monopolies are bad because they hold too much market share, have high pricing power and can stifle innovation in their industries because of their power. Compared to a competitive industry, a Monopoly would produce less of a product and charge a higher price for the product. and we break up Monopolies to make the industry more competitive. Basic Microecon classes at universities teaches us all this. This is not the point of my blog.

But Microeconomic theories (atleast the ones I know) have always looked at Monopolies serving the end consumer - like AT&T, Standard Oil, Microsoft etc. but what about those companies that act as monopolies to manufacturing companies - like a Walmart. Walmart almost dictates pricing terms to its suppliers and the suppliers don't have much of a say or choice to go somewhere else to sell their wares. If they don't sell to Walmart, they pretty have to shut down a large portion of their production capacity. This pressure from Walmart then pushes these companies at first to seek efficiencies in production in the US and after that they can only get those costs down by moving to a lower-cost overseas operation. But this causes these companies to lay off employees in the US. So are we increasing unemployment in the country by having these kind of Monopolies like Walmart - they may not be charging a high price to a consumer but extract low prices from their suppliers. Google is another example. They hardly charge anything from a user for e-mail or its search function from a consumer but it has almost 65% of the market share in the search space. They can dictate terms to the companies seeking to advertise on its search pages. I am just raising a question whether Monopolies should strictly be looked at from the point of view of how they behave with a consumer. Is there a potential fallout for an economy by having companies with monopolistic power with their suppliers? What we pay for something is earnings for another. Porters five forces does look at all the sources of power for an industry - should the govt only look improving the bargaining powers of a consumer in a Monopolistic industry - should they also not look at improving the bargaining power of suppliers?