“You’re so pure.”
Not a matter of purity. A matter of politics and principle and strategy. The GOP had been corrupted into a big government, open borders, forever-wars party under BUsh, McCain and Romney. That had to end, and it could only end by defeating them at the polls, to clear the way for a new kind of leader.
And how much more damage did Obama do in those four years? Even Trump cannot get rid of it.