People are just sadistic
No it doesn't help. There is also no theory behind why it works. You briefly traumatize the body with ECT and as a result you can't access your feelings of depression anymore and they get a positive result on the Hamilton depression scale. Then after a few months when people have somewhat processed the trauma, their old feelings come back. But psychiatry calls this a "relapse" for which they need "maintenence" ECT (which happens in 50% of the cases). So people will continually receive ECTs. This also mostly happens to people who are defenseless and to old people. It's the biggest joke in science there currently is, but psychiatry loves it
My hospital psychiatrist sat next to my bed with a wide grin while I was tied to the bed and they administered the anesthesia, so I'm sure they are not sadistic