Don't forget the Dems have designated "Super Delegates".
This mechanism was created by the Dem Establishent after the Dem electorate selected libs, Mondale and Dukakis, in the '84 and '88 primaries, only for Dems to get blown out in those General Presidential Elections.
It was "Super Delegates" that helped bring Dem Centrist, BIll Clinton, to power at the Dem 1992 Convention.
The Clintons leaned on "Super Delegates" in 2008 and 2016 Dem Primaries to help put Hillary at the top of those Dem Presidential Tickets.

But, those cow-pie tossers in the 2008 Iowa Dem Caucuses had the audacity to give the win to Obama over Hillary. Imagine that.