But does that make it against the Circle of Knowing's principles? No. Summoning is a means to an end and they're perfectly okay with it. The entire point of Living on a Prayer and the End of an Era cinematic was to summon twelve at once.
I have a question... If the Twelve are summoned primals, why didn't the Circle of Knowing go all dark-n-evil when they were summoning them. o.O/