The US did used to have rules preventing too much concentration of media ownership.
Then the telecommunication act of 1996 happened and jettisoned a bunch of those rules “to foster competition”, which in fact predictably reduced competition. Later action prompted by the act (2003) made it even worse.
It has always been the case that rich & powerful folks tend to own media, but for a while we had pretty effective rules preventing any one entity from controlling too much of a given media market, which tempered that tendency. We got rid of much of that, with predictable results.
The problem is the concentration. One person majority owning a platform as influential as Twitter or an expansive media empire (Murdochs) is not good for democracy. If the empire was split up to ten different multimillionaires we'd be better off.
In the UK we have the BBC where every word is considered to be a fact. They have TV channels and radio shows where 'today's curated and extremely edited sound-bites' are broadcast every 30 minutes, 24/7.
At least with billionaire owners it's taken as read there is going to be some nuance.
Laurene Powell Jobs buying Atlantic, Jeff Bezos buying Washington Post, Elon Musk buying Twitter.