If they're so concerned about the rising number of ones partaking, why don't they just shoot out an BOE letter scolding the elders to be very discerning about who to officially count as partaking. That would seem to at least lower the number or slow the growth at worst.
Maybe someone else will be able to confirm with more certainty than I have, but I could've sworn I read that there was indeed some procedure that elders follow in order to determine who is "rightfully" partaking. I don't know what it is, but I think at the very least they weed out all non-JWs.