When Comrade Bernie sued the DNC (and Hillary and Lil' Debbie) for politically sodomizing him during the 2016 primaries, the courts ruled the DNC can select their candidate by any manner they choose, including setting aside the desires of the primary Democrat voters. So much for one-man-one-vote or small d democracy.
Very true, there are a lot of things about our so called 2 party, or 2 faction system that seem extra-constitutional and arbitrary.