People talk about the Democratic presidential nominating process like it's straightforward and fair.
It's not true that the DNC picks the nominee nor that voters have a free choice. Name recognition, money, party support, media, and yes, charisma all factor in.
The establishment white guy usually wins because they have support lined up and are deemed "viable" compared to progressive, non-white, or women candidates. And against someone like Trump, voters are scared of "unviable" candidates.