The idea behind the stressors is that, as
@Stunned said, it tells the plant to hurry up and finish... the end is near. Official scientific studies may not have been done yet, but I have repeatedly done this experiment over the last 5 or 6 years, as have others, and every time, I have seen a significant increase in the length and width of the trichomes as compared to a plant that did not get the treatment. These studies are documented in several of my grow journals on this site. If forming a hypothesis, doing a controlled side by side experiment, and documenting the results through microscope picture studies is not science, I don't know what is.
Also, logic prevails in this discussion, since we know that our bright lights degrade the trichomes. Since we are putting the plants into darkness for 36 hours, that is at least a 12 hour daytime that was not experienced. That is 12 hours where the trichomes did not degrade because of the light, but yet they were still allowed to grow and ripen for that entire 36 hours, in the dark. If you chop at the end of this, your buds never get that degrading bright light for that entire day and a half, and that change is enough to see a difference big enough that it can be seen with the naked eye.
I know that all of these techniques work, icewater, screws, drought, splitting the stem, reducing the room temperature and the power of the lights and even the amount of daylight they get all that last week. If you haven't tried a side by side and seen this effect for yourself, you are missing out. Not everything what we know about these plants is yet written in scientific journals, because in most of the world, growing this stuff is still illegal. Give us time, and all of this will be common knowledge as official research catches up with the practical world.