Tons of people do Zoom from poorly lit rooms. Not because they prefer not to be seen, or go for the gothic vampire aesthetic, but because they don't know any better or don't have good lighting in their home office.
I'm not disagreeing with that, I'm saying they are still lit, even if a little. if the human eye is able to see in such conditions, why not an electronic device?
Sensitivity and dynamic range of the human eye is far, far better than any camera sensor you can buy at a reasonable price.
On top of that, you are looking into a light source. If you were reading a book or newspaper you'd probably want more light.