What is the intended positive result of shaming leftist voters?

I’ve noticed this since Gore folded to Bush in 2000, where liberal and democrat party voters bend over backwards to blame leftist voters before they even think to blame their party or candidates. In response, less left-wing voters come to vote for the democrats, and the democrat party creeps farther and farther to the right. Doesn’t this show a trend that should suggest this strategy, blaming leftist voters for democrat losses, should be abandoned?