Thats not very stupid at all. If your power were to go out for a prolonged period of time, it would be very detrimental to your grow. Your plants would possibly hermie up on you and then youd be left with a finish product filled with seeds. This happened to a friend of mine because 1000Ws tend to fry digital timers. His final product was a beautifully dank crop that had around 60g of seeds per pound.
Putting the plants in sunlight or ambient light wouldnt fix do much for the plants, but it'd be a helluva lot better than leaving them in an unscheduled dark period.
(you might wanna learn a little more about plants and growing before you damn peoples advice.)