This is a Circe's personal opinion post. (ie, it doesn't necessarily reflect that of the team as a whole)
How do we decide who the first 25 or so are?
When we announce events, people pour in, usually many at once, all on the same cell.
I can see it resulting in a lot of people having a go at GMs for being left out, and after a GM has been complained at for a good half hour or so (sadly, we always get a bunch of event guild or PMs to us about the event as it is, including, incredibly, choice of event), they usually don't feel in a mood to go host another event.