Power concentrations are increasing in today’s media landscape. Reasons for this include increasing structural and technological dependences on digital platform companies, as well as shifts in opinion power and control over news production, distribution, and consumption. Digital opinion power and platformised media markets have prompted the need for a re-evaluation of the current approach. This article critically revisits and analyses media concentration rules. To this end, I employ a normative conceptual framework that examines ”opinion power in the platform world” at three distinct levels (individual citizen, institutional newsroom, and media ecosystem). At each level, I identify the existing legal tools and gaps in controlling power and concentration in the digital age. Based on that, I offer a unifying theoretical framework for a “digital media concentration law,” along with core concepts and guiding principles. I highlight policy goals and fields that are outside the traditional scope yet are relevant for addressing issues relating to the digital age. Additionally, the emerging European Union regulatory framework—specifically the Digital Services Act, the Digital Markets Act, and the European Media Freedom Act—reflects an evolving approach regarding platforms and media concentration. On a final note, the analysis draws from the mapping and evaluation results of a Europe-wide study on media pluralism and diversity online, which examined (national) media concentration rules.