This completely depends on the reader's lighting conditions and time of day.
If I'm sitting on my laptop in daylight, outdoors or in a room with large windows, I'd really like to max out the contrast while reading. Later in the day, the "Night Light" feature that's built into Windows 11 will reduce the contrast and increase the color temperature towards a yellower hue. (In past years I used f.lux for this.)
This kind of adjustment is not something each website should try to do. It's a system-wide setting that needs to take into account e.g. local sunrise/sundown times, like Night Light does. (And on iPhones, there's a light sensor that takes care of this.)
Videographers would recommend using the full dynamic range that is available, right? That way you are providing maximum detail and letting other systems (e.g. screen, room light, human visual system) scale as appropriate.
Even if your scene were in the middle of the night you would still use your brightest white ("FFFFFF") for the least-dark moonlit areas. (Striking recent example is The Northman fighting in the caves.)
In that context I wonder if the motivation for recommending near-white and near-black, i.e. foregoing dynamic range for no intrinsic benefit, is for contrast against other things in the user's field of view e.g. large images, browser toolbars, popup notifications, etc.
If I'm sitting on my laptop in daylight, outdoors or in a room with large windows, I'd really like to max out the contrast while reading. Later in the day, the "Night Light" feature that's built into Windows 11 will reduce the contrast and increase the color temperature towards a yellower hue. (In past years I used f.lux for this.)
This kind of adjustment is not something each website should try to do. It's a system-wide setting that needs to take into account e.g. local sunrise/sundown times, like Night Light does. (And on iPhones, there's a light sensor that takes care of this.)