Winner takes all means we all loose.Most elections in recent years have been very close. Trump lost the popular vote and still became president. Does that give him a mandate to run rampant on our government institutions the way he has? Of course not. Republicans slim majority in the Senate. Do they really think this means all the American people support what they are doing? Of course not. It means maybe half of the people support what they are doing. And when you factor in the margins by which each candidate won, and the percentage of people who voted in each election, their slim majority really represents maybe 30% of Americans at best. So no one has a mandate. If the party in power by the slimmest of margins pushes through their most extreme agenda they are going against the will of the majority of Americans.
Recent events bare this out. Polls were very clear that the majority of Americans do not support Trumps's Muslim ban, the Republican tax plan, the FCC repeal of Net Neutrality, or the leasing of public lands for oil and coal extraction. Yet Trump and Republicans moved ahead with these things anyhow.