[ygra]

Venting the moisture also vents the heat. A modern dryer uses a heat pump for both heating the air and pulling the water out of the air. Although I guess with lifetimes of the devices and the relative cost of power (or gas even) between NA and EU they might be much more common around here. With an insulated house you also don't really want to have too many holes in the building, especially not ones intended to remove heat.