Include IRE or false color to see image tonal luminance in percent

What problem do you see this solving?

Adding IRE or "false color" to identify luminance percent over image will help to see the skin tone luminance to get perfect exposition from subject faces as example.

RAW softwares as Rawtherapee, include a button to activate overall image luminance identification shown by color which represent the luminance percent per image zones

With this tool we can be able to see how bright is the white zones, how dark are the black zones and how bright is the skin tones so we can easy adjust a correct luminance level for a particular image/scene.

This luminance zones changes their color in realtime during image retouching process

When was the last time you were affected by this lack of functionality, or specific tool?

Everytime I use Capture One, I miss this feature