The problem with saying "They can need it for their desyn" is, when do you draw the line? The only reason people can't need on every single thing to desyn is because of class restrictions, and I'm sure as hell that the developers didn't have the foresight to see this being a problem when they incorporated desynthesis in the first place (along side other updates in 2.3 such as the hunt.) I've seen worse reasons for people needing on equipment that isn't an upgrade, even as little as GC seals (and we're talking level 20-30 dungeons here, its worth less than a FATE or supply).