The biggest difference between the two parties is not that one tilts left and the other tilts right, but how their respective leaders play their hands. Democratic Party leadership plays up to its base, which responds, predictably, with loyalty. Republican Party leadership has contempt for its base, which responds, predictably, with resentment.
The blame is not all on one side. Even resentful Democrats practice party discipline. Resentful Republicans wait until the ship is in sight of the port, then set it on fire.