Spare the rod, spoil the child
Children push the envelope to see how much bad behavior they can get away with before they’re punished. The Democratic party has done precisely this. THEY are the ones so "extreme" in their policies, the general populace has seen them as irrational, unjust and insane.
This absurdity flies under the banner of, "give em an inch, and they take a foot." It also demonstrates "give em enough rope, and they'll hang themselves."