The Loyal Opposition
We don't really have a blueprint for what a "loyal opposition" looks like, do we? Take the periods from 2008-2010 and then 2016-2018. Putting the filibuster aside, that's when we had (mostly) one party rule. During those times, there was little for the opposition party to do aside from either vote with the ruling majority party or kvetch from the sidelines about what the majority was doing. The former constituted disloyalty, the latter, weakness. Millions upon millions of people voted for representatives that were confined to minority status and (almost complete) powerlessness. Game theory - almost - dictates that such scenarios should make people vote for candidates that they didn't prefer. Better to have a candidate that you disagree with and has power that can be leveraged and positions that can be influenced than one that's utterly powerless, rendering their ideology meaningless. We need to square that circle as we shouldn't have representatives that.