Sweating cools the body by evaporating off the surface off the skin. Once it starts dripping off the body the effectiveness of the cooling is reduced and you’re losing water for no gain and heading towards getting dehydrated and hyperthermia.

Sweat is not fat being burnt off.

For sweat to evaporate, the surrounding air needs to be relatively dry.  A static air environment will result in the air surrounding the body to be humid thus reducing the evaporation rate and cooling effect. Once sweat starts accumulating on the skin it’s a sign that it’s not able to evaporate and is not cooling the body. This is when you need to turn up the fan otherwise  your body will take action itself and reduce the amount of blood flowing to the muscles restricting the amount of power (work) and thus generate less heat. Otherwise you will start to feel signs of heat stroke.

By keeping the air moving past the body, the air will remain drier and continue to cool the body more effectively.

Thus a good flow of air is necessary for you to have a more effective training session.

In basicaly, more sweat = less gain = wasted training