I don't know about vape oil but neem oil is there to help protect my cannabis plant from unwanted insects and pests. I use it once a week and there is no sign of side effects shown in my cannabis plants yet.
I think you have some point here. The absence of light actually stimulates plants to grow fastest at night. I will share the link to the article which proves this theory. Do Plants Grow At Night? - Smart Garden Guide.
There are lots of things to know before growing cannabis, like the space you want to grow marijuana, understanding the signs of nutrient deficiencies, pests, growing costs, etc.
I think the reason behind using pot fertilizers is they can supply nutrients to your plants immediately. It is especially effective for giving fast-growing plants, like cannabis, an extra boost during the growing season.