The concept of urban living is evolving, and there is a growing interest in creating smaller, more connected, and hyperlocal neighbourhoods, where everything people need is within a 15-minute walk or bike ride. This paper challenges the concept of the ‘15-minute city’ as a panacea for urban ills, by exploring the history of utopian urban planning and regeneration aimed at creating sustainable, inclusive and vibrant communities by desegregating disadvantaged groups. Specifically, we examine social mixing policies, which are recurring top-down interventions that pathologise concentrated urban disadvantage. We trace the evolution of these policies in Europe from the Garden City movement to post-war social housing redevelopment to the current 15-minute city, which we consider to be social mix by stealth. While such policies can reduce the degree of concentrated disadvantage in the short term, they tend to be ineffective in the long term, as deprived neighbourhoods often remain so despite attempts to make them more diverse. The paper argues that the 15-minute city would be implemented through de facto social mix actions at the neighbourhood level, which are insufficient to address the deeper structural issues that perpetuate spatial inequality and deprivation. We propose that longitudinal and comparative analyses, combined with ‘right to the city’ perspectives, should be considered in future research and policymaking to understand – and more importantly address – why urban renewal initiatives that aim for equitable outcomes at the neighbourhood scale ultimately fail to deliver.