Purpose Our paper aims to address an open question in the scientific literature about Wikipedia: the structural logic behind two seemingly contradictory trends – peer-leveraged crowdsourcing and gatekeeping of core participation. Design/methodology/approach Using the complete dataset of the English, Spanish, and Italian versions of Wikipedia (2001–2020), we analyzed metrics such as the number of articles, creations, or edits performed by users. We calculated their distributions, adapted the Gini index to measure participation inequalities and employed network science methods to understand user-edit interactions. Findings Our analysis confirms significant disparities in content generation and engagement, emphasizing content editing. However, we demonstrate that these differences coexist with extensive collaboration. Specifically, our findings reveal that disparities in participation levels and collaborative editing complement each other. Curatorial leadership by a central group of contributors is extremely collaborative, while occasional contributors intervene flexibly in specific contexts. Originality/value High participation levels do not necessarily equate to high engagement. Our analysis shows that the inequalities in agency characterizing Wikipedia’s creation and editing process stem from a high barrier to curatorship. This inequality fosters the self-selection of highly committed editors, whose sustained efforts underpin large-scale collaboration. Such collaboration, in turn, encourages new contributors to make occasional yet valuable interventions. This interplay between sustained curatorial efforts and flexible participation is a cornerstone of Wikipedia’s success.