First off, I don’t need to FIND a fault in the Mechagnomes, your faults are plain to see in that diaper you’re wearing.
Chi, or Spirit connects every living in the universe. Explaining abilities like Touch of Death and Paralysis. We Know chi naturally flows through objects in a specific way from Legion, and that altering chi floes takes a great deal of Effort.
Therefore, a Mechagnome monk would make himself worse as a monk by cutting off his arms. At least until such a point that your training allowed you to reconnect the flow of chi, in your new, dead arms.