The urbanism movement exists to help remedy some of the downsides of urban living. One of which is social alienation and isolation as a result of the scale and diversity of cities.
No, it exists to fix the problems caused by car-dependent suburbia. Inner cities can have problems too, but a lot of those are created by cities wanting to support suburban commuters rather than the local community.
Suburbia came into being as a result of urban dysfunction. Cities have existed and had problems since long before cars were invented. People nowadays really love to blame everything on cars lmao, if only it were that simple
Cities were literally demolished to run highways through them, cutting right through vibrant communities to do so. Auto companies lobbied governments and ran public relations campaigns to change the law and societal mores to make car-centric infrastructure and norms the only way things are done. Ripping up public transport, inventing the concept of “jaywalking” (itself just a form of car-centric victim blaming), and banning the building of more people-friendly communities through strict Euclidean zoning.