Everytime the Dems lose, they go to the center to find votes. And they find them! That's how Bill Clinton won, he went to the center (some say right, whatever). Gore went a little left and then lost. So Obama learned to not run left and instead ran on broad "hope". His reward for passing the ACA was losing Congress for his last 6 years. Thanks voters. Clinton went a little left on climate change, supposedly the important issue for the left, and lost. So Biden learned to not run left, and he won!
Every time the Dems go left they lose. So they go to the center to find voters and they find them. And you wonder why they go to the center?