Yes, you can legally do this where it is allowed, but other than that, it is pretty much a copout. Not everyone can grow things well. Not everyone has a green thumb. Also, weed is not the easiest plants to grow and takes a lot of time and effort to get quality flower. It's also not like you can just walk over to plant(s) whenever you want to smoke up. The plant has cycles of when it is making flower and when it's not. Now, you can trick it out with grow tents, lights, hydroponics, etc, but now you're a freaking grow house and most people definitely don't want that.