Originally posted by Kento
It may have strictly been something that required the special abilities of an Uzumaki though. That may be why the host has always been an Uzumaki.😑 And talking about Uzumaki just made me realize.....EVERYBODY in Konoha had to know Naruto was the Fourth's son.....So I was definitely wrong.
Also note, Killerbee said that if the Kyuubi broke free during the mental training, the room had been designed by the cloud to be able to contain it, meaning that there are means of sealing the kyuubi besides jinchiruki.