Wheelchair Armrests do offer some benefits, however. Wheelchair Armrests allow you to rest your arms at a height that is higher than your lap. When you place your arms on the wheelchair armrests, you take the pull of gravity off your arms and shoulders.
The extra weight of the arms might actually pull you forward, causing a slouched posture. With the weight of your arms resting on the wheelchair armrest, you might be able to straighten your spine and sit more upright.