It's like this by: Jacki Cammidge, Certified Horticulturist
A humidifier is similar to an air conditioner, in that it takes moisture out of the air, and collects it for disposal. Whether you dispose of it down the drain, or on your plants, it doesn't care how.
For your plants, as long as it's liquid, they don't care either! All they require is the water, not the minerals and softeners and added chemicals that are sometimes in well or tap water. So, yes, a good option.