Grow tent light leaks vs full moon outside grow?!?

I'm wondering if someone can explain something for me...as a newbie, I read all kind of posts, articles and videos that talk about how important (Critical?!) it is to have NO light leaks in your grow tent during the flowering stage...ZERO! However, when growing outside, in nature, there IS a big "light leak"...nightly. The moon.

So what's the difference? Thanks, all!