To be fair, I haven't seen many of them. They exist, but I don't think they tend to be very successful in the West; there's a market for martial arts steeped in mystical fluff, but the Omoto-kyo Shintoism that the more esoteric aikido branches are rooted in is deeply weird even by Japanese standards, and it doesn't fit particularly well with the watered-down holism-and-wellness narrative that Western students who're so inclined tend to expect.

The branch of aikido I'm most familiar with is Yoshinkan, which is one of the earlier, harder ones.