It fragments the labour market, a key benefit of living in a large city
Not sure I agree with this. Not every job is super specialized and except for job commuting, we should get every other kind of trip (groceries, entertainment, visiting doctor etc.) within a 15 minute radius. There is value to be had with decentralized but these "satellite" places should be built with efficient connection to the main job centres until they can develop their own niche overtime.