I believe the concept of “superdelegates” came from the 1972 nomination of George McGovern and the disastrous results that followed in the general election. The party wanted to make sure that wouldn’t happen again and created superdelegates.
These extra delegates would toe the party line and adhere to the mandate pushed by DNC leadership to make sure somebody without the apparatchik approval could get nominated. Bernie seems to be an example of why superdelegates were created in the minds of the party. The fix was in before the first ballot was cast back in Iowa.
Sad that a party that proclaims itself to be one for the “common person” is spitting in their membership’s faces now. Many will likely sit at home this November in protest and the DNC deserves it.