International Naturist Federation INF-FNI

For some reason I have surprisingly never heard of INF-FNI until today.  When searching the list of national federations, I found that the U.S. is not an affiliate of INF.  Does anyone know why?  I know the U.S. has the American Association for Nude Recreation organization (which I am a member of), but why does AANR not become a part of INF-FNI to broaden connections and promote American naturism internationally?

Maybe I sound silly by asking this because I don't even understand what a membership with INF-FNI fully brings, but I welcome all who know a thing or two about INF-FNI to spill all.
Thanks