We have to start talking, and listening to people who don't agree with us.
I sympathise with points made. But as an Australian, I must point to the role played in this state of affairs by your First-Past-The-Post electoral system. Our preferential system (plus proportional voting for the Senate) has just yielded a winding back of Trump-channeling polarisation (in the winning of government by the Albanese Labor Party). Even the major parties have to pay minimum respect to minorities and subsectors. Not all values have to be aggregated and weaponised for wedge strategies.
I agree in principle to the idea of listening to people who don't agree with us. I've done this while canvassing door-to-door for relatively liberal candidates (specifically Democrats) in purplish red states such as Montana. Quite a few Republicans and other right-of-center Trumpaholics are willing to tell you that all Democratic "libtard" candidates suck and some even are willing to provide a reason or two to explain their thinking. I haven't found these kind of exchanges of much value or interest, though, since it seems as though most of the time I've merely heard somebody parroting what they have heard on right-wing corporate talk radio such as Limbaugh and his ilk, or else right-wing corporate broadcast media such as Tucker Carlson and his fellow propagandists at Murdoch Misinformation Media, Inc. So in practice, I think I would prefer to get a root canal at the dentist's rather than spend half a day on the receiving end of vitriolic sloganeering from Trumpaholics during a door-to-door canvassing session.
I agree that the so-called Howard Dean "scream" was actually more like a slightly loud cheer or expression of enthusiasm--and did not sound demented except when anti-leftist ideologues and corporate media personalities intentionally snipped it out of its context of a campaign speech and amplified it. Dean was on the fringes of the D.C. corporate-friendly Democratic political establishment, sort of like fellow Vermonter Bernie Sanders, and thus was frequently subject to scorn when not being ignored altogether. Unlike Trump, Dean was not puffed-up celebrity who was a lucrative candidate to cover. During that campaign, Edwards and Kerry were preferred by the Beltway party establishment. It turned out the Kerry's patrician unwillingness or inability to fight back against those thuggish Swift Boat attackers was a key factor in his loss to Bush Jr. (along with voter suppression by Ohio's state Republican machine). If Dean would have managed to overcome the scream smear campaign and become the Democratic nominee, I think he would have fought back more effectively against similar attempts at GOP character assassination than Kerry did.