Hybrid fiber–wireless access networks are commonly framed in the literature as systems that integrate heterogeneous technologies to extend coverage or improve performance. While this integration-centric perspective has yielded important architectural innovations, it has also ob-scured a more fundamental driver of real-world broadband deployment outcomes: the asymmetric concentration of cost, time, and operational constraints across network segments. This paper proposes a conceptual shift from “technology integration” toward “segment-level substitution” as the dominant logic for hybrid access network design. Drawing on broadband deployment litera-ture, techno-economic studies, and infrastructure management theory, the paper argues that hybrid architectures are most effective when wireless technologies are selectively substituted for optical fiber in constraint-heavy access segments, rather than uniformly integrated across the network. A segment-based analytical model is developed to distinguish feeder, distribution, and access com-ponents of passive optical networks (PON), and to explain why deployment inefficiencies dis-proportionately arise in the last-mile segment. The paper introduces the concepts of constraint concentration and feasibility-gated substitution to formalize when and where wireless access can outperform fiber on deployment efficiency dimensions without compromising service require-ments. By reframing hybrid access networks as decision problems rather than purely technical architectures, the paper contributes to hybrid networking theory, broadband infrastructure eco-nomics, and strategic network planning. The framework provides a foundation for future empiri-cal validation and informs both operator strategy and public broadband policy.