Jesus Christ. Do you know how the Republicans have turned America into a right-wing hellscape?
Incrementally.
They inched the Overton Window right every time they won. Every time some egg said "If nobody's offering universal healthcare I'm not voting" they get to set the terms.
You egg. A far left candidate would lose to Trump so hard that the climate would be forced to turn into magma without any more help. Elections are about choosing the better of two options. Nobody us going to put up a candidate you agree with on everything: no such candidate exists.
It was doing fine where it was.