It's an Asian thing.
As you point out, in most Western Airlines an extra crew member in the jumpseat is regarded as a safety bonus. Three pairs of eyes for the price of two.
In Asia - cannot!
Why?
Ahhh....cannot lah.
It's like the training systems. Throwbacks to the dark ages, while the civilized parts of the world have moved on from the "torture box" routine.
You're meant to be glad to have a job, and pray the nice people on high will let you keep it. That's no exaggeration.