Thirty years ago your mom would likely be listening to talk radio, if that's the kind of media diet she's looking for. There's lots of deep reasons why people consume what they consume, I just think it's wrong to attribute a lot of agency to these platforms.
It's actually comforting to think that twitter, FB etc are destroying discourse when in reality it's people on the sites, out of their own volition, or through (lack of) education, socialization, etc.
My mom is in her 70s. She was a peace corps volunteer, a health care provider and an advocate for regulation of certain medical providers. She carried petitions for Al Gore. Not somebody that republicans would knowingly talk to.
But places like Facebook push content that your friends like. Sometimes that’s so and so’s new baby. Other times it’s Uncle Bob’s manifesto on why critical race theory is doing whatever.
Social media isn’t a boogeyman responsible for everything but it is a critical channel to influence. My mom gets bombarded with crazy tales of Joe Biden taking gasoline away, etc. I get lots of crazy dramatic fundraising requests from EFF, broadband advocates, etc.
It’s real and it works.