While I am also concerned about the breakdown of political discourse in the USA (and, to a lesser degree, the UK), I don’t think it’s reached the level of late Weimar Republic.
And, in the same sense, we do not have the same level of polarization: we don't close the opposition newspapers, only websites/social network accounts, so definitely not the same, we don't ban parties yet (just harass them through selective law enforcement and impede their ability to raise funds) and only one party so far has the enforcers (coincidentally borrowing the name and attributes of the one of KPD from 1920s). Also, economically, we have much lower inflation.
In the same sense that Boris Johnson was appointed PM by Queen Elizabeth II; constitutional systems in which the head of government is appointed by the head of state, based largely on control of Parliament, but sometimes with bounded discretion where there is no clear parliamentary majority, are rather common models.
Had Hitler’s party not won the plurality of seats, or had other parties that could work together in a coalition had more seats, he would not have been appointed chancellor.
Controlling the largest bloc that can work together is winning a parliamentary election; not as total a victory as winning an outright majority, but—in the constitutional and political context in which the Nazis did it—a rather sufficient one.
