Well it is obviously a bad thing, and goes to the heart of antitrust. US regulators understood this clearly all the way up until Reagan, and his DOJ instituted

Well it is obviously a bad thing, and goes to the heart of antitrust. US regulators understood this clearly all the way up until Reagan, and his DOJ instituted a paradigm shift that let companies get away with obliterating their competition through acquisitions - instead of assessing whether companies could compete in a healthy market, the focus became solely the impact on consumers. That’s why, under this new-ish paradigm, Amazon is fine, because prices are kept low through monopolistic and monopsonistic effects. The EU has a better enforcement paradigm that says a healthy economy can only exist where new market entrants can also earn a living, even if it means consumer prices aren’t the lowest they could possibly be.