It's not as concentrated crazy or immediately dangerous, but all mainstream religions have some pretty mental ideas when you step back and think about it.
I'm not sure you'll get agreement on how many may have died due to the WTS teachings, and whether it's a net loss of life vs those they help prevent.
But the JWs are not at the same level of "cult" as what most people imagine a cult to be ("heavens gate" type).
Maybe if we measured things in potential life-years lost, it would be more clear-cut - you don't have to have been killed to have years of your life taken away.