Yes, some other PDGA events have filled in 15 minutes. But this is the first time both Worlds have almost filled so quickly. All over the world players on waitlists or not yet registered are wondering if they'll be able to get in. The host teams are looking to see if they can handle more players than originally expected if schedules get adjusted to allow more players.
Some members (okay, maybe a bunch) have been wondering how the initial division size allocations have been made for Worlds. But more importantly, the allocations almost always get adjusted maybe a few times before each Worlds as the actual registration numbers continue to stream in.