It is indeed! Volcano could, I suppose, monitor the purchases of attys/cartos, but that would lead to an argument every time there was a warranty claim.
So far the US distributor has come up with lame technical reasons which are nothing other than a veiled justification for screwing his customers on the consumables like attys/cartos-the razor/razor blade marketing concept. From the prices that are on AliBaba (Chinese website for products made in China), he is also taking a hefty mark-up of 300% on the kits as well. In all fairness, though, the posted price on AliBaba needs to be confirmed.
Correct me if I am wrong, but I know of no other PV retailer who imposes such a ludicrous restriction.