Because redoing the primary is an absurd idea

And I am, probably to an excessive and embittered degree, made cynical by the amount of open propaganda in and out of the media which is attempting to put out bad ideas on purpose to hurt the Democrats and help the fascists

And you’re not wrong. A contested convention would be a massive shit show which might doom the Democrats in the election irrevocably. But it would be feasible to do. Holding another primary election would not.