If you think about it, letting Club Level ("concierge") get a 90-day booking is no different than what they do on
DCL. On DCL, they have check-in priority tiers, but if you are sailing concierge you go first, regardless of your
Castaway Club status. On most sailings, it is very unusual for any of the
Castaway Cay cabanas to go to anyone but concierge, for instance.
Club/Concierge is being sold as a higher service level. But really, for Club Level, all it's been getting people is snacks and booze. They killed itinerary planning, in part because if those guests only got 180/60 planning like everyone else, it's not all that effective to have those concierges doing the bookings for dining and FP+, being able to do one guest at a time, sequential, while others are online simultaneously doing their own bookings.
By "adding time" to concierge, giving them advance booking on the bourgeoisie, it means that they can look at itinerary planning as a benefit again, because if the Club guests have the extra lead, it is then possible for a concierge to do sequential bookings.