> constrain supply, raise prices far beyond what the constraint justifies, and then refuse to lower them

In a healthy competitive market, this doesn't work. In a Ronald Reagan / Robert Bork / Consumer Welfare Standard market, where the idea that antitrust policy should promote competition is scoffed at and all M&A is allowed so long as a business can scribble with crayons on butcher paper a tall tale about how their merger will totally reduce prices (pinky promise!), an unhealthy low-competition market is the intentional and inevitable result.