Let's put an example:
Kakashi warps a Kunai with a FTG seal on it, if minato wants to do to the other dimension where the kunai is, he wouldn't be able to because HE NEEDS A BLACK HOLE to do that (black hole= warping barrier that kamui creates).
Kakashi warps a Kunai with a FTG seal on it, if minato wants to do to the other dimension where the kunai is, he wouldn't be able to because HE NEEDS A BLACK HOLE to do that (black hole= warping barrier that kamui creates).