You were kinda correct. Trump becoming the big Republican nominee was part of the Pied Piper strategy of the establishment Democrat party. The Hillary Clinton campaign intentionally uplifted radical conservative candidates in an effort to make winning elections easier. The logic was if the Conservative party looks crazy, the Democratic party can run on simply pointing out that craziness without needing to actually have specific policies or positions. The establishment Democrats loved the idea of doing less work, so they eagerly adopted the strategy and focused on crushing their own left flank candidate Bernie Sanders.

The Clinton campaign and the DNC had done a bunch of oppositional research on Donald Trump in preparation, but chose to sit on it, not wanting to tank Trump’s chances of becoming the nominee. They focused instead on Jeb Bush and Marco Rubio.

This is why the US has a bunch of feckless Democrats who never seem to run for anything, only against Republicans. They keep running this same, “vote for me or you’ll get the crazy man” strategy, even though they keep losing with it.