While blockchain technology (BCT) has emerged as a disruptive force capable of redefining trust and transparency in global supply chains, its adoption among Small and Medium-sized Enterprises (SMEs) remains critically low, resulting in a severe digital productivity paradox. Existing literature predominantly attributes this technological lag to financial constraints and complex technical requirements. This study challenges the traditional cost-centric paradigm by exploring the underlying cognitive, organizational, and institutional factors driving SME decision-making. Utilizing a qualitative, exploratory research design, 22 semi-structured in-depth interviews were conducted with strategic decision-makers across five SME sectors in Hungary. The theoretical framework synthesized the Technology Acceptance Model (TAM), the Unified Theory of Acceptance and Use of Technology (UTAUT), and Institutional Theory. An innovative "negative proof" thought experiment—assuming 100% external funding—was applied to rigorously isolate cognitive barriers from financial constraints. The findings reveal that the primary barrier to adoption is a fundamental cognitive gap: the lack of technological awareness, profound fears regarding transparency (e.g., GDPR conflicts, trade secrets), and exceptionally low perceived business usefulness. Furthermore, SME innovation strategies regarding decentralized networks are structurally reactive. Adoption intentions are almost exclusively driven by coercive institutional isomorphism—specifically, the mandates of dominant multinational partners and regulatory compliance—rather than internal innovativeness. These insights emphasize that BCT must be treated as a socio-technical system, necessitating proactive mentoring from large corporate integrators and targeted regulatory frameworks to bridge the technological divide.