It's even worse than that -- there hasn't been a genuinely open Democratic Primary since 2008.

• 2012: Obama is a popular incumbent, that's the only one they get a pass for
• 2016: The obvious plan was for Hillary to be coronated, the only serious challenger wasn't even from the Democratic Party, there was the ratfucking with the superdelegates, Dems argued in court that they had no obligation to run a fair primary, etc.
• 2020: Ratfuck Pt. II with the coordinated dropout/endorsement of Biden
• 2024: No one challenges an obviously senile and unpopular president, then the party forces him out and subs in someone who didn't even get any primary votes in 2020