Not that it matters to any of us since we can all access NIN regardless of if it is gated behind 2.2 or not, but how do we know ninjas aren't in Eorzea prior to 2.2? As far as Yugiri knows, they aren't...but does she know every single Doman alive that may have somehow escaped to/infiltrated/immigrated to Eorzea? I'm sure she has too much to deal with to keep track of every single ninja from her land. Maybe one or more slipped through without her knowledge and formed a clan secretly in Eorzea? So maybe they can exist prior to 2.2.