The need for a neutral or negative tilt has everything to do with typing style and user orientation. If you’re a floater, with your hands not touching the keyboard except at the fingertips and with your body high enough to not encourage wrist extension, a positive tilt can be desirable. If you’re a planter, where you prefer your wrists or forearms anchored to palm rests, a tabletop, or chair armrests, then a neutral or negative tilt is desirable. Avoiding excessive wrist extension is the goal.