The rule that actually changed everything
The real shift came through Olympic Agenda 2020, the IOC's reform package, which gave each Games organizing committee, not just the IOC itself, the power to propose additional sports specific to its own edition. Since Tokyo 2020, an organizing committee can put forward one or more extra events, and if the relevant international federation and the IOC agree, the full IOC Session can add them for that Games only, with the decision required no later than three years before the Opening Ceremony. Critically, a host city's selections do not bind future hosts. Tokyo's organizers used this new flexibility to propose skateboarding, sport climbing, surfing, karate and baseball and softball for 2021, and the IOC Executive Board formally backed the package before it went to a full Session vote. That single procedural change, moving the proposal power from Lausanne to each host city, is the reason the sport list now looks different at almost every Games rather than shifting only once a decade through a slow, centralized review.
