And like Bernie, another relatively non-establishment candidate that could have given people something actually new to vote for seems to have now been taken care of, once again with some fancy footwork (cherry picking of polls this time) by the DNC.
It's pretty hard to not vote for the same people when anyone that doesn't fit the proper mold isn't handicapped through the nomination process.
I'd post some supporting links, but for every article I could post supporting my thesis someone could easily post one that denies it. Articles and discussions on such topics are rarely substantially based on facts, the whole thing is largely propaganda.
The best commentary I've heard on the subject of nomination shenanigans in both parties has been from Dan Carlin (of Hardcore History fame) on his lesser known podcast "Common Sense with Dan Carlin". He knows a thing or two about history and politics, and he is fairly disgusted with the entire political system in the US.