Simple Response, Candidates Matter. Political party doesn't mean a thing to me. It's the candidates that matter. 2016, both Trump and Clinton would have left this country in far worst shape when either one left office than when either one first entered the office. The only way to vote for no harm was voting against both and hope for a miracle. Candidates matter which you don't seem to understand. There's a lot of folks who aren't very partisan, who aren't political party oriented. Whose political ideology and philosophy falls in-between the two major parties, not of the far right or the far left.
As the GOP moves further to the right, the Democrats to the left, more and more folks are deserting those parties. More and more people aren't that extreme either way. This has led to the rise of independents, the less to nonpartisan, rising from 30% in 2006 to 41% today or as of 14 Aug 2019 according to Gallup.
Be my guest and nominate a Sanders or a Warren, perhaps they'll win. But like Hillary in 2016, I think quite of lot of those in middle America, I mean ideological and philosophical wise politically, not geographically. Will once again be voting against both. They don't like Trump, but they don't want someone from the extreme far left either. The only choice left, vote third party or stay home. My opinion anyway, for what it's worth.
Those who associate or affiliate with either major party, I don't think they understand how far out of the mainstream politically, each major party has become. Those who do identify with each major party, think they are mainstream when in fact they are not.