That old bromide is so demonstrably false that I am amazed that it’s still around…yet it is. Like herpes we just can’t seem to eradicate it.
Way back when I was a new shooter I figured this out by getting behind my bed in my dark bedroom, and pointing my unloaded gun at the night-light (barely) illuminated hallway. I could easily ID any person in that hall, but the light near me, or it’s lack thereof, wasn’t sufficient to see the sights.
Pretty damn easy experiment to try. You’d think that anyone promoting the shibboleth above would’ve, too.
So if you want to hit precisely in true low light, you need either a white light or night sights. Both are a good idea.
On the other hand, Tom Givens’ data indicates that lack of sufficient light to make a good shot simply wasn’t a factor in his students’ shootings. So while most shootings do indeed, as we’ve all be taught, take place in low light after sun down, the data (for civilian self-defense shootings) suggest that insufficient light to either ID your target or see the sights sufficiently well simply isn’t an issue. Good to know!
There’s an old thread over at pistol-training that is full of gold on this subject, and I refer you there for wisdom.
For my part, I’ll just leave you with the thought: Why are so many demonstrably false things and bad tactics still being taught?