Why do male gymnasts (nearly always) train shirtless?

The official dresscode is leotard plus long pants, shorts only for floor-performance. In training most of male gymnasts go shirtless over pants,in warmup before competition they use to have their leo sagged down to the waist with their chest bare, and they only get fully dressed for the (short) moment of competition. Immediatelly after performing they tear their leo down again and may pull over a T-shirt or a jacket. I thought it might be inconvenient if the lycra gets wet by sweat and sticks to the skin, so most guys tear their leo down to have it completely dry in the moment of performance?