Of course they talk about all the really wacky ones everyone knows about, Jones Town, Charles Mason, Heaven's gate and Branch Dravidian.
However if you add up all the unnecessary deaths these cults have contributed too (a thousand and fifty people) it pales in comparison to the number of people who have been directly or indirectly killed my the Jehovah's Witnesses.
By the way all of the cults mention above are no more, except for the Watchtower Bible and Truck society.
The little ones seem to get all the attention and the big ones just slide on by.