Very little in human history has had the reach of those websites you're talking about, and on those users tend to be in their own bubbles. On 4chan, with its millions of users over the past couple of decades, attention is centered around a few boards.
For better or worse, TV is paid for by advertisers. On the upside, that does put some limits on how objectionable the content can be before nobody's willing to pay for its distribution.
On the downside, it does away with ethical and quality standards, in trying to maximize viewership while minimizing cost, which in turn tends to make the content objectionable anyway.
I remember TV from my childhood being just people shooting each other and screaming at each other. Advertisers didn't have any problem with that, or with monsters tearing people apart or with gangster rap.
Counterpoint, the owners and showrunners of those TV channels decide what is aired and how, so a lot of TV channels have become propaganda outlets for one side or another. Most infamous in the English speaking countries is News Corp / Rupert Murdoch, who has pushed a right-wing, anti-lgbt narrative for a long time now.
I just thought of television as something much more fragmented and localised compared to the billion and more poepie flowing through the same Facebook funnel. I'll grant you that some things in the past did transcend boundaries and gain global reach but those I counted amongst the referenced "few things."
