You're trading individual reasoning away in return for immunity from blame if things fuck up. One of my friends used to train employees in this (retarded, I think) manner to work at the coffee/ice cream shop. She wouldn't tell them "why" they were doing anything, and instead made them "just do it", and the end result was that they took zero initiative and also zero responsibility when something went wrong outside the immediate sphere of their responsibility.
For example, you had to press a certain button on the register for a certain type of item. She wouldn't say why you had to press that button instead of just keying in the price. "Just do it, don't ask." But when the button broke, people were totally helpless and couldn't ring the item in at all, when if she'd simply said, "That button logs how many of X item were purchased, and the owner is tracking how popular they are" then people could simply have smoothly shifted to keying in the price and manuallly tracking how many of the item were sold. Instead of standing helplessly by and saying, "I'm not sure, but I think it might fuck up the register if I key that in, since we were told NEVER TO DO THAT, so I can't sell any of those until the boss returns my phone call!"
The military's like that, which is why so many soldiers feel like they aren't responsible personally when they do terrible things. Because they were taught to do what they were told without questioning "why", and they did exactly that.