We don't know the background, and I would also assume that cheating may take place.
But I make a clear distinction between a festival/marathon on the one hand, I buy a ticket in the online shop and expect nothing more. I made it today for the festival in Metz. (Of course, I understand that the organizers like planning stability, given the high costs of such an event.)
For me, on the other hand, an encuentro is a personal matter, it is unthinkable that my partner would sit there in front of the door and wait. Such a faux pas simply should never happen to the host, as he can phone me in time. Yesterday I signed up for an encuentro, months after the deadline. And my partner received a confirmation even before she filled out her form. (Of course, I knew that the host would like to see her at his encuentro.)