It requires you to have 4 mana, and have 3 artifacts in play IF you pitched it. It's regular mana cost is less prohibitive than its alternative. AFAIK the removal that's being played in vintage is swords to plowshares or bounce. Not gonna happen.
But Bazaar negates almost all these drawback and how often are you not going to hae 3 artifacts in a Stax shell? Not saying it's goning to happen, but not as bad as you make it out to be.