Less cars is a worthy goal for some people in some places for some activities, and works in tandem with making the cars we do have better.

83% of the US lives in urban areas and the US has the highest transport emissions in the world.

"This doesn't work for literally everyone so let's do this other thing that isn't as good"

Bicycles win when the level of density is still relatively low. If we are serious about efficiency, bikes don't make that more sense. Sufficient density so that most activity can be done on foot, and the rest is mass transit.