I think you are going overboard in search of hidden meaning. Wiz most probably just meant that for every side, all their ships's FP are added to one total.
I agree I might be overthinking it, but given that Wiz was specifically using words like "smaller" and "larger" in reference to the numbers of ships/fleets this seems more logical. Namely, it would mean that the introduction of the FDCB would actually have a chance to resolve the DoomStack issue instead of just altering the appearance of it. If it was just down to FP, then yes, the FDCB is completely, totally useless. However, if it's actual raw numbers then it actually makes sense.
It also mitigates the complaints regarding a hardcap on the size of an individual fleet. Commanding 30 Cruisers is presumably no harder than commanding 30 Corvettes - you've got the same number of pieces on the board, as it were. If you have a restriction on bringing only so many ships to a single battle, it makes much more tactical sense to adopt proper fleet compositions and have a mixture of lights and heavies, including point-defence/pickets and carriers along with a glass-cannon or two in order to maximise your fleets ability to be useful/adaptable in different circumstances. If you look at real-world naval strategy, you never see a fleet deploy without a mixture of different combat roles, and you also never see multiple fleets trying to operate in the same area above a certain number of ships per square km. If the entire US navy were to try and effectively fight that of North Korea there would be a lot of ships getting in each others way or not being able to contribute to the battle, even if the battle took place in the middle of the pacific with hundreds of square km available per ship (not unlike the availability of room to maneuver in space!)