I'd say the more salient dynamic is mass communication increasing the power of propaganda (now individually tailored!) making it so people are increasingly tolerant those lines being crossed. People voted for this, right? There are legitimate understandable gripes underlying Trumpism. Propaganda is able to use that frustration as raw input, and twist it to convince people to support things that directly make their gripes worse! How much did we hear about inflation and the price of eggs, and yet forty trillion dollars more in the hole and now they cheer for it.

Sometime during the Obama years I came up with the realization that the primary information flow in democracy (especially a two-party democracy like the US) isn't the commonly accepted people->government, but rather goes parties->people. The act of "choosing" a candidate makes people have an affinity for everything that politician goes on to do, even when they would have rejected most of it. Trumpism, specifically how people who considered themselves "conservative" didn't look at his abject failure of a first term and send him permanently packing in favor of someone with leadership or patriotism, has thoroughly proven this out.