We're 0-2 in those instances because we were never given a choice. In 2016 Hillary was anointed the nominee before the race even began, and the party sandbagged Bernie from the jump. This year Biden refused to step a side, like he had previously promised mind you, and the party once again thrust a candidate on us we never chose.
My party has a lot of problems to fix (get rid of identity politics, DEI horseshit, send the far left to the back of the bus where they belong, ect), but becoming more democratic is at the top of the list.