People don't have to be less intelligent to be victims of media manipulations. Carlin, the American comedian was being glib.
I'm something of a news junkie. I observe the drama in the same way others might watch a daytime serial. From this view, I have to admire the craftsmanship that goes into spinning and developing media narratives, the way they expertly play upon the heart-strings of the masses. Often times the viewers are all too willing to indulge their outrage. Putting aside the concept of intelligence entirely, the masses who have little time or curiosity to observe the news in-depth, are poorly matched against the master propagandists. They've had decades to hone their craft.
As you say, you're concerned about the status of democracy in the US. Yet here comes the new narrative of domestic terrorism, buoyed by the same fears expressed in this thread. The masses are outraged. The image of Trump as a Hitler-like figure has been burned into their minds by repeated invocations of Godwin's law. After repeating this ad nauseam, Biden now proclaims that Trump is like Goebbels,
“You say the lie long enough, keep repeating it, repeating it, repeating it, it becomes common knowledge”
Even I have been called a Nazi for challenging what I see as irrational. Posters here have insisted that I check my privilege in regards to race. All of this without knowing my identity, race or experiences.
While I share your concern about civil society devolving, I see it as coming as a reaction to Trumpism. The intolerance is easy to see from where I stand, and I'm no fan of Trump. The comparison to ISIS is part and parcel of this intolerance. I find it somewhat ironic that you appeal to valuing democracy (I read that as civil society) while indulging the assumptions and fears I've outlined above.
https://www.politico.com/news/2020/09/26/joe-biden-trump-jos... https://www.youtube.com/watch?v=brgZSzmAA3c https://www.youtube.com/watch?v=BnA-ghhW_WI