The fractiousness of American politics is due to its diversity, not its political system. Shifting to a proportional representation parliamentary system would be unlikely to change that. Look at how politics in Italy or Israel compares to that of the Nordic countries. All of those countries have similar political systems.
I don't think the U.S. is as diverse as Italy or Israel, but you are correct that the U.S. is, indeed, internally diverse (e.g., the great gap between Massachusetts and Alabama). I still think the adoption of a German-style parliamentary system would likely turn down the heat in American politics greatly.
The fractiousness of American politics is due to its diversity, not its political system. Shifting to a proportional representation parliamentary system would be unlikely to change that. Look at how politics in Italy or Israel compares to that of the Nordic countries. All of those countries have similar political systems.
I don't think the U.S. is as diverse as Italy or Israel, but you are correct that the U.S. is, indeed, internally diverse (e.g., the great gap between Massachusetts and Alabama). I still think the adoption of a German-style parliamentary system would likely turn down the heat in American politics greatly.