Urban highways primarily function to channel commuters to-and-from the city limits. If there were less of that exchange in commuting patterns, they would not be necessary. It's not about uprooting the car infrastructure entirely, but reducing traffic to the extent where it can flow effectively without these humongous blights diving our neighborhoods, spitting pollution onto its residents, and putting everyone at risk who needs to walk past their exits.

Highways ought to encircle a city's perimeter and terminate when they enter the city limits. The rest of the way, the traffic can move at speeds safe for pedestrians. Philly actually does this much better than most other cities in the US, but we should still make sure they don't expand further - otherwise, the only outcome is more displacement and urban blight.