If a small number of people are allowed to own the vast majority of media outlets, those media outlets are no longer going to represent the interests of the public at large.
Back when all television/radio was broadcast over the air, there used to be this quaint concept of broadcasters having to prove that they serve "the public interest" to receive and retain an FCC license to use the public airwaves.
https://www.benton.org/public_interest_obligations_of_dtv_br...