Here is my thoughts, the plant sugars that make plant expansion available within the plant come from photosynthesis. That happens in the leaves. If you remove the fan leaves, any energy the plant stored in those leaves and even if a tiny amount of light hits those leaves they stay green or have on Lilbit then they will make even a tiny bit more plant sugars. If your plant has an abundance of plant sugars, it makes more foliage, more buds, more roots....win win...removing the fan leaves removes an important amount of those sugars, watering down your plants overall potential within the sap of the plant.
Ok here comes my craziness, I sit and reason stuff out so it makes sense to me, it may or may not have any basis in truth, but it makes sense to me.
Ok, healthy plants have high pressure within their stocks, this pressure holds their fans and sugar leaves upward because that is the direction they grow naturally in the plant structure, everything is angled upward from the stalk. Imagine an air pump increasing the pressure within the stock of the plant from below, low pressure (droopy leaves) shows general inability of the root system to support the foliage (low power pump).
Ok here comes the synergy, dump tons of light on healthy happy fan leaves, they do their photosynthesis magic and dump their manufactured sugars into the plants vascular system and intake more nutrients and water to continue working. This plant sugar "sweetens" the sap, lots of sugars available allow the root system to expand increasing the plants ability to uptake more nutes and water and generate pressure in the stalk. The roots have to have good uptake, so salt build-ups are a no-no, excess nutes are a no-no (don't clog the uptake), bad ph is BAD, as long as you have available what the plant needs more is less, lowering the ability of the plant to make the needed pressure lowers production and if you see where trichomes form on leaves, it is as if this structure is ballooned out of the surface of the leaf by pressure from within (at back edges where the vascular pressure would be highest)...I conjecture that is exactly what is happening and keeping high sap pressure (leaves pointed up and happy) will increase your resin production and harden your buds with sap instead of making fluffy bud.
This process involves different things for different systems but is basically healthy leaves and roots = healthy vibrant producing plant.
Tuck the fans, if you play just a bit, you can learn to weave the leaves tips together below the buds and they can't pull apart for some reason, the constant upward pressure from the sap in the stock making the leaves hold onto each other and they are rough leaves so they stay together.
Wow ramble city...
To be honest I have no idea if that is the mechanism, but makes sense to me from what I have seen in my grow an other grows with the healthiest looking plants.
If I made any botanist's chuckle then it is a good day..
brother.