That strawman argument is at the level of "I voted for a pigeon why isn't he president".
We have email evidence in 2016 of a very popular primary candidate (Sanders) being plotted against by an organisation that is supposed to uphold democracy.
A similar occurrence happened in 2020 when Sanders was up against Biden. Stalking horse candidates were used to soak up votes which were then pledged to Biden. He had no support without those votes.
Saying that people have the option to choose a candidate at the primary stage is demonstrably false.
And we have evidence that Sanders lost by 8M votes. Called an election. Move on. Or I guess keep denying the agency of millions of voters because your first baby crush candidate lost.
Bro you are the one who literally just invented a claim and rolled it back when you got called out.
As far as the DNC rewriting its rules, surely you know that they significantly reworked the rules from 2016 to 2020 based on feedback from the Sanders campaign, significantly reducing the power of the superdelegates.