From what I understand from reading both of your posts is, in a way you're both right.

The both of you stated that at night the stem grows or "stretches". Due to its biologic adaption for survival. Meaning, grow taller to ensure it wins the battle for light.

Both of you in way or another has said that new foliage does not grow at night.

So I interpret this as there is no new foliage growth, due to the plant using all it's stored energy to grow/stretch the stem.

With that said, you would assume that the roots also do not grow at night, because all the plants energy is focused on the stem.

This makes since to me since I've seen a lot of posts around here about when going to 12/12 the plant stretches and root growth slows down.

But hey what do I know
That's just my :twocents: