Some gyms are also not really 100 percent sure of what the team levels and divisions will be by the time comp season begins. Sometimes when you make teams true level, everyone is not happy with that and they leave to go elsewhere where they can be on a higher level team even if they don not have the skill. Add in financial issues, scheduling conflicts, personality conflicts, "Suzie must fly" or else and there is a lot of movement during the summer months.
With so many roster changes these days before choreography and the first competition it may change a team from Level 3 to Level 2, Coed 5 to Coed 4, from Coed to All Girl, or from a worlds level 5 division to a non worlds level 5 division. By not posting until you are absolutely sure avoids the whole "they changed divisions to avoid competing against us" - translation losing - drama when in reality they could not be competitive in that division due to internal athlete movements.