The problem with wifi is a momentary stall due to interference will result in dropped frames. You wouldn't notice this normally since during general web browsing a 1 or 2 second delay loading some image is barely noticeable, but streaming is much more demanding on your connection as it's a real time service. You also have no idea when interference will strike, you could be streaming fine for hours then a neighbor turns on netflix or a microwave comes on and suddenly your connection is fried.