They're your plants, you raise them however you want.I strongly disagree with this way of thinking. Granted, the plants have no way to expel excess nutrients but cutting back or eliminating nutrients near the end allows the plants to utilize any stored nutrients and only uptake water and/or water and cleansing agents. I've done it both ways in organic soil, soil less and hydro and plants that have been flushed always produce a product that is less harsh and smoother to smoke. I've also discussed this subject with representatives of both House & Garden and Cultured Solutions. To the man they all agree that cleansing the plants near the end product a better product. Since they know more than I do on the subject, I'll take their word. As I said, my own experimentation backs up what they have told me.
I will always be honest with new growers on the basic science of plant biology and let them make up their own minds.