Agreed. It's extremely common for K-pop groups to release fanchant videos. For example, Pixy, under Allart Ent., releases fanchant guides, and so does Cix, which is under C9 Ent.
Curious for the concertgoers here who aren't based in Korea - have you heard the crowds do the chants before? I've been to a significant number of concerts, but I very rarely hear the fanchants. Usually, there's a tiny tiny subset that's doing the fanchants, and everyone else is just hollering. That's not a bad thing! I was just curious if your guy's experience has been different.