If..
a) You like to keep your HP below 75% or 50% to activate latent from other pieces of equipment.
b) You complain a lot about the stupid WHM in your party keep curing you to 100%.
I feel sorry for the first ones to pay the current price of 3 mil for this thing, go out to an Abyssea party, drop a Souleater > Guillotine (or something to that effect), then wonder "wtf?" as they are unable to be healed. XD
FYI apparently its been confirmed that you cannot be Cured While you have this belt on.
Its likely the "Strong" Curse Effect, Cannot Recover HP/MP while this belt is equipped, but this is not confirmed, Just "Cannot be cured" is confirmed.
Not 100% useless but if you insist on using this belt then you have to pay a lot more attention, see a cure coming in then you've got to swap it out and you can still get away with it.