Despite significant interest in the influence of digital platforms, we still lack a theoretically grounded understanding of why platformization processes and outcomes differ across contexts. In this article, we address this gap by developing a field-theoretical framework that conceptualizes platformization as a field-level transformation process shaped by the structural conditions of strategic action fields (SAFs), including actor constellations, patterns of interaction and mutual awareness, and shared understandings about purposes, power relations, and rules. Empirically, we present a comparative analysis of platformization processes in three business fields – logistics, mechanical component manufacturing, and orthopaedic technology – drawing on 89 interviews, survey data, and ethnographic materials. Our findings show that platformization is limited by the specific structural conditions of business fields. These include the organizational complexity and heterogeneity of user firms that curtail standardized solutions, the long-standing relational networks that reduce intermediation opportunities, the importance of domain-specific experiential knowledge that platforms struggle to replicate, the strong bargaining position of users and complementors, and the complexity of formal and informal regulation. These conditions result in distinct platformization processes that diverge from the ‘winner-takes-all’ dynamics observed in consumer-facing fields. Instead of platform dominance, based on strong network and lock-in effects, we identify outcomes such as marginal and partial platformization and even platform shutout. Platforms remain confined to niche segments, coexist with incumbents, or are absorbed into existing structures. Overall, the article contributes to platform studies by shifting the analytical focus from platform-centric explanations to the broader socioeconomic contexts in which platforms are embedded. It highlights the need for a more nuanced understanding of platformization that accounts for variation across fields and challenges generic claims about the dominance of platform organizations across society.