Another take is the "moderate" will always vote for their party regardless. By nominating an extremist you get out the vote of those who normally stay at home. Trump was an extreme candidate but the "moderate" Republicans stuck with him. I feel the same thing would have happened with Bernie. The "moderate" Democrat might have shaken their head a bit, but they it wasn't like they would vote for a Republican.
This is the sort of flawed analysis that has likely plagued Democratic strategists and resulted in the party being so needlessly impotent over the past few decades. It doesn’t account for the (problematic) winner-take-all mechanics of the electoral college. Furthermore, according to Gallup in its most recent poll on the issue, 36% of the electorate is independent.
