I agree with you, but it's important to note that the 8 bits of dynamic range are not in constant luminance steps. The gamma of most monitors is about 2 (1.8-2.2) or square law. This is done to roughly match your eye's sensitivity. So those bits have a range of about 64,000,000:1 in brightness. What your monitor can do?? Well, that depends a lot on your monitor and the background illumination of the room.