No it doesn't make sense. You should not be able to capture anything darker than 40, or brighter than 60 if you are limited to 40-60. (actually by the file format, not the sensor, sensors today have higher dynamic ranges than 8 bit sRGB) It should not turn 40 into 0 and 60 into 100.
In real life, a logarithmic brightness scale (which is how human perception works) goes from negative infinity (zero energy) to positive infinity (infinite energy) – excluding both endpoints. 0 is not the bottom, and 100 is not the top.
In real life, photographs are printed on paper. The brightness of light reflecting off paper depends not only on the colour of the paper, but on the brightness of the illumination. (Likewise, photographs displayed on a computer monitor depend on the screen's brightness.)
In real life, human brightness perception depends on the brightness of the environment. An LED can look bright in the dark and dim in sunlight, and range dim to medium to bright on a cloudy day without anyone really noticing that the clouds between them and the sun are thicker or thinner.
In real life, there is no 0. There is no 100. Your comment doesn't make any sense.
Right. Metering is even now with scene programs and AI still basically a complicated negotiation about establishing middle grey -- when there may be no perceptual middle grey in the scene at all (black cat in coal bin, polar bear in snow)
The narrow band of sensitivity of a film or sensor has to be sort of moved to where it is needed (by controlling how much light gets in or for how long) according to the result the photographer is likely to want from their photo.
Even the most basic of film dead-reckoning methods -- Sunny 16 -- relies on subjective input from the photographer:
It's trivial to take an image editor and any existing image that is as you describe, and adjust the black point to 40 "percent" and white to 60%. It won't look more correct or realistic at all.