Light period and manipulation. Could you imagine moving a weed plant all over your house searching for the sunny windows? Also what if the house has low E glass. Or what if......
Also due to light refraction, reflection, and diffusion caused by the glass will reduce the amount of lumens directly given to the plant.
Inside grows better under HID
Outdoor grow requires a certain amount of direct sunlight to maximize the plants growth. Also having a 5' plant in your window is not the most stealthiest way to grow. IMHO