Madara has seen the eighth gate, meaning it predates Minato.
So too has Minato.
We know it's a forbidden technique (no, not the fodder that listens to drake.) and Minato probably put it in the seal of scrolls just like he did the Kage Bushin.
Several of the techniques we've seen from it to date are associated with Konoha (Primary lotus.) as well as phrases ("the lotus of the leaf blooms twice") along with Konoha Shinobi being the only people that have shown it off.
I'm gonna throw a curve ball here; look at who rivals Gai and Lee: