The DNC is a private entity, and can act (internally) just about any way they want. You and I are free (well, constrained by finances I suppose) to establish our own parties that act however we want. Freedom of association and all.

People don't have to join the Democrats or the Republicans. Those who do make that choice are now learning that these parties function exactly like any other corporate entity. Some sort of oligarchy calling the shots over a pseudo-democratic process that they ostensibly claim to be the real process. Time for the schisms.

Someone didn't pay attention in civics class. You'd prefer the federal government to manage the decisions of all the major political parties?