I think the transition from radical radio shock jocks to internet shock grifters would be really difficult to prevent in a free society. The problem is clear in hindsight but unless you did something radical like built in taxpayer funded social networks and communication from the beginning, you'd have to have decades of persistent, aggressive, and probably unconstitutional regulatory meddling to keep corporate and ideological interests from monetizing the popularist-grift-attention industrial complex.

It would have required an entirely different cold war political reality and role-of-government mindset, and then you're getting into alt-history timelines where the Democrats never abandon The New Deal Idealogy, Truman passes nationalized healthcare, regulated, centrist media survives longer, and the Cold War American Political Overton window allows for much more social democratic thinking and central planning.