Quite - it is (potentially, not always I feel) child abuse. But as it's being pushed as a technique to "control children not otherwise controllable", I think whether it works or not at least needs to be answered - if it doesn't, it's just abuse, end of story.

And although it may be horrifying to people (I'm disturbed by it), if it IS effective, and does work in cases where other methods have failed - is it truly a bad thing?

That's why I think the question of "does it work" needs to be answered, to see if there's any benefit whatsoever, or if it's just abuse.