I don't know that it's any more complicated than Wear//Tear costs 2 mana to kill artifacts.
I do think that Wear//Tear is the better card against Oath - beyond being an instant, attacking mana can be pretty relevant against Inferno Oath decks planning on ramping to
6 drops. Still, Fragmentize is fine in the matchup and much better against workshop decks. I think generally people are more concerned about their Workshop matchup right now, and Jeskai players who are worried about Oath (like myself) have access to the probably-better-than-wear//tear Containment Priest.
Still, there probably is a deck that wants the card - either something that's very short on anti-Oath/Shops slots and can't afford to run Cages/Priests, or something that has excessive anti-Oath/Shops slots and can afford Wear//Tear in addition to Fragmentize/Cage/Priest ... I don't know what that deck looks like, but it's plausible