It’s a shit message, but they’re apparently permanently damaged by the 1980 landslide re-election loss to Reagan and incapable of moving on. IDK if liberal democracy will survive here long enough for us to see if another wing of the party can ever get those folks to let them try something else.
[edit] not for nothing, Obama lightly hinted at a move away from that in his campaigning (if not his governing) and it seemed to work pretty damn well. Why they didn’t double down on that is anyone’s guess, but I’d suppose it rhymes with “bobbying”.