I personally live in North Carolina, from the days of Bill Clinton, through Bush, and Obama, they all were more in line with Biden then the actual left. As time went on, socially they were dragged kicking and screaming to the left in terms of gay rights and stuff but economically they have gone further and further to the right.
Sanders was the first actual pull to the left the party actually has had that wasn't shrugged off. The main reason why they didn't mind him in 2016 was because they thought he was a joke and a token opponent for Hillary. Once he actually gained traction and they saw where their base actually was, they fought tooth and nail and he is the only reason why we have the ones we do now. The DNC largely thought the left was just a fringe they placated for votes not realizing just how much of their voters it actually was. Now they fight them.