I dry in the light but not strong light, its more a factor of light intensity and if you take a light meter to a room lit by a household bulb you will see that although it looks light to us it is in fact quite a low intensity.
You can cut a small sample and experiment leaving the rest in darkness. Its easier for new growers to use darkness lest they give too much light which id guess is why the advice reads that way.
I also have light leaks when growing but none are enough to make photosynthesis start up and plants flower as normal since it is technically very dark inside the tent.
Growers be lazy after a while and see that its not a hard and fast rule