The word "stealing a kitchen" is the jargon of the chef industry. The chef steals food, which means that the master teaches his disciples to cook, but he will not teach them all, but he will leave a hand at the bottom of the box and cannot spread it out easily.
On the one hand, this will give the apprentice room to play, on the other hand, it will also prevent the apprentice from copying his own back road and deliberately leaving his back hand.