Brightness is increasingly a critical spec for monitors. In the realm of video content, brightness is in part responsible for achieving HDR quality. When dealing with photography, brightness makes colors on the screen look more vivid. Therefore, many monitor manufacturers focus on increasing the nit rating of monitors as much as possible to present their products as more technologically advanced.
For color-critical professionals like photographers, this is not necessarily a benefit. While higher brightness might make things on the screen look better, there might also be an unintended color accuracy effect. Screens and printers display images in very different ways and making sure these match as closely as possible means making adjustments within very well-defined parameters.
Besides color space specifications and calibration, adjusting brightness is another step you need to take to obtain the most accurate results..