If you use a vented dryer and vent it into the house, I bet you are correct. 

But these ventless dryers as I understand it now that others in this thread have pointed it out, they work differently. If I understand it correctly they dry the air much like an air conditioner dries the air and lets the water from the air drip to somewhere outside the house. The heat pump in the ventless dryers I presume work in the same way and the water goes into the drain like a washing machine water goes in the drain.

Pretty ingenious. That is if they keep working for a long time. So far so good for only a couple months. We will see. Wife really likes the one we have so far.