Yes, but there are a ton of radio stations and cable/TV stations , many of them independently owned. So what if there a dozen companies with vertical ownership? The FCC still regulates and I think their recent ruling of 45 % by large companies is reasonable, given the high capital costs required.
Remember, there was nary a word when it was just GE, Viacom, etc. NYT Corp. owns how many newspapers? Gannet and Hearst have huge horizontal monopolies (and all their newspapers editorials sound the same), and I dont remember the Left getting exercised by any of that.
The recent ruling by the FCC has been distorted, primarily because the Left is out to silence Murdoch, not because of some bogus concern with "diversity". (Many if not most local stations use network or AP news anyway, did you notice?)
The original complaint against monopolies is that they resulted in a stale, uncompetitive business environment. If you listen to almost any radio station these days, the word "stale" perfectly describes what you are hearing.
I live in the New York radio market, and over the last couple of years the radio market has gotten rather bizarre. First, we started hearing advertisements on FM music stations for AM news or talk stations (the stations were owned by the same conglomerate). In the last few weeks, I've started hearing ads on one FM music station for another FM music station that plays a different type of music.
I'm not an old-fashioned person by nature, but radio was far more interesting when the radio stations didn't all sound the same.