> So a part of a standard which maps color to specific brightness levels is pretty much irrelevant outside of the unrealistic case of a perfect calibrated monit

> So a part of a standard which maps color to specific brightness levels is pretty much irrelevant outside of the unrealistic case of a perfect calibrated monitor in a perfect environment. Which does exist. But again is for most internet users unrealistic. If you modify the brightness in software, you can also tonemap it properly and retain the contrast easily.