the middle is enabling the extremists. Currently, political parties can precisely slice the electorate into blocks and divide it close to 50% (not the total votes, but the power – see Senate at 50%, House at 51%, Electoral college by 10Ks of votes). So, when it is impossible to change any of the voter preferences by reasoning, then all you can do is outrage people so that more of them actually vote (as US has lower voting rates than other countries) and engage extremists. Then, politicians are reluctant to offend those easily-offended crazies to such degree that, for example, Trump who did great things in vaccine developments can’t praise that without being booed.
Trump expressed the same in much shorter way, addressing the Black community with “what do you have to lose”? It is now acknowledged that he significantly moved Hispanics to the right, so there is some hope. Not sure whether any English-speaking electorate is capable of changing their opinions.