There is always a sorting out of voters when there preferred primary candidate calls it quits. Sanders voters defected no more than any other previous primary voter whose candidate called it quits.
The exception was Hillary supporters in 2008. They broke in larger numbers for Romney rather than vote for Obama. Telling of the Clinton coalition.

Sanders supporters were then and still are being made the scapegoats of a thoroughly corrupt and incompetent party’s chosen nominee.

Did you get that- party’s chosen nominee.

But but but the rules.....