It's as if collapsing politics into one dimension makes it hard to identify distinctions

Liberalism includes the right of private property, which is definitionally at odds with leftist thought. Points for social liberalism I guess, but when social goals are viewed through the narrow lens of individuality it misses giant, glaring social structures that arguably have more impact over individual liberty than state governance does.

"most successful left party in the world" is a contemptible assertion.