I had not heard of superdelegates till this campaign, but the idea strikes me as a sensible one. The point is to stabilize the two-party system. For each party to have a chance of winning, both parties have to compete for the center. That usually happens; but there is a risk that a party will be excessively influenced by zealots (the "base") who are essential to its morale but who cannot deliver enough votes for a victory in the general election. Then the other party has the center to itself and wins a lopsided victory -- Johnson over Goldwater in 1968, Nixon over McGovern in 1972. The existence of superdelegates -- professionals who (one hopes) care most about winning the general election -- is (I suppose) supposed to protect against that eventuality. Unfortunately, it is not a foolproof scheme. Professionals sometimes care more about preserving the party organization and/or their power in it than about winning any particular election.

What would happen if *both* parties were captured by their bases? In nasty circumstances that might lead to civil war, but in America I think it would more likely give a third party a serious chance. That might lead to the demise of one of the old parties, or to coalition government as in much of the rest of the democratic world. I do not find any of those prospects attractive. Thus, tho I myself am an extremist on many issues, I do not fancy extremists (even of my kind) taking over either party.