Dems correctly assessed in '16 running radical crazy Bernie would would not sell with the centrist voters
@spartansstink mentioned any candidate must win in order to win the general. While his income redistribution schemes were perfectly fine with the Democrat far Left, the party did all in its power to make sure he wouldn't win the nomination because he was too far Left for the country.
Hillary wasn't necessarily any less radical, but she was more sellable as a "moderate"...same thing with Biden who was presented as a moderate, but has governed further Left than even Obama! Trump is anti-establishment, just like his GOP base. Matter of fact, the GOP party establishment hates his guts just as
@SoCo said. However, the GOP doesn't have to try to present Trump as more "moderate" than anti-establishment. This is directly in contrast to what the Dems had to do with Hillary. Trump's appeal to both GOP voters and moderate general election voters
IS as anti-establishment!
If
@spartansstink is correct, voters will prefer someone who is more tied to bigger government than against it. Trump's appeal is against bigger government, and I'd suggest more voters can be found anti-establishment than pro big government. However we shall see, I could be wrong.