The concept of autism has undergone a significant transformation in recent decades, evolving from a narrowly defined, rare disorder into a broad and heterogeneous spectrum. This diagnostic expansion, while intended to improve recognition of diverse presentations, has led to a marked increase in prevalence and a dilution of autism’s neurobiological distinctiveness. Two emerging trends may further contribute to this phenomenon: the rise in adult diagnoses without documented childhood traits, and the growing attribution of transdiagnostic social difficulties to subthreshold autistic traits. These trends risk conflating autism with general social dysfunction and undermining the validity of related clinical constructs. The diagnostic inflation of ASD may reflect a problematic overextension of criteria, compounded by the use of unstructured assessments and amplified by the growing influence of neurodiversity discourse. Moreover, it is facilitated by the absence of definitive neurobiological markers and remains at odds with autism’s characterization as a neurodevelopmental condition with strong genetic roots. Whether this expansive reconceptualization constitutes progress or regression warrants deeper scientific debate.