Comparing current elections to historical elections misses one critical factor - the internet. Before the internet existed, the MSM controlled what info the voters received. That is no longer true. 

Additionally, the computers never forget anything. So past failures can be right up front for anyone who takes the time to look. Campaign promises don't mean much when anyone can look up a candidates previous record and determine whether the candidate delivered what they promised or said one thing in the campaign and did the opposite when elected.

That is essentially "What Happened" to Hillary Clinton. She's still operating on the assumption that the MSM controls information flow and that bad behavior in the past will be forgotten. It's demonstrated by her comment on Bill Clinton's sexual escapes being "in the past". Now that people can see all of their history without the filtering of the MSM, they reject candidates based on their past behavior.