Possibly because some people love to see other people run about screaming and tearing their hair out as a result of their amazing litle superpowers of Confuse and BullSh@@?
Or possibly it's all just ignorance compounded with incompetence and bad timing? I dunno, that's what I see at work, anyway. It's often impossible to tell the difference, from the results, so for my bunch, I'll go with Occam's Razor on this one, and call all it stupidity in motion.