It's beyond stupid; it's absolutely retarded... and the cause of the only mishap I've ever taken at height.
A new groundie had placed a leaking oil jug in the gear box on top of my climb line; my rule is saws/gas/tools on one side, climbing/rigging gear goes on the other (separate boxed, in other words).
The following day, he'd removed it, and put it where it went, while never realizing the gravity of what he'd done.
As a result, on my next climbing job... the rope was oily in a spot, but it had soaked in. I noticed nothing when I unfurled the rope and climbed up. I hit about 60 feet or so, when all of the sudden, my hitch failed, and I went screaming down to the ground, and landed on my back... HARD. The operative part of the friction hitch is the FRICTION... and I had NADA. I walked away from it, but my hands were fried from trying to slow my descent, and I was bruised pretty good.
ALWAYS KEEP THEM SEPARATE!!!!!!
I tossed the rope and prussic cord. And the groundie, too.