Ves actually did not know whether other mech designers were able to employ the same trick with masterwork mechs.
It was not as if he hung around a lot of other masterwork mech designers and inquired about this specific topic.
That caused him suspect that they probably couldn't. One of the reasons why Ves was able to do this was because he could send out his companion spirit to a masterwork mech across vast distances.
Unless other masterwork mech designers also possessed a way to project their spiritualities away from their bodies, it was probably a lot more difficult to get anything done.
Still, Gloriana never demonstrated this particular ability despite possessing a companion spirit of her own. Then again, Alexandria wouldn't have been of much use as she did not possess any strong powers or abilities that could make a difference in a massive fight.