You obviously haven't tried this
I did try it, go back a few pages for my report. I eat the "e-diet" normally, and added the chocolate at much higher levels than were even recommended and kept chocolate as the only variable from other rolls (set, setting, dose, product, all controlled for trying to be as scientific as possible). And this was the second time I tried a chocolate pre-load.
It did not have any effect on our rolls, but I can't say it doesn't work for others and you have to always account for placebo effect--that's just good technique. Would love to see a double-blind study on it since there are so many supporters. I'm not advocating for or against it; if it works for you, great! I was accused in an earlier post that my cynical attitude causes a negative placebo effect, but on the contrary if anything my attitude was the opposite--I really did want it to work, I mean why wouldn't I want to find something that improves our rolls???
Plus, you have to also be aware that when some users are extolling the virtues of chocolate on their roll, they may also have been trying the new diet at the same time, thus not really knowing which of those variables is responsible. You would have to conduct a multivariate experiment with controls for placebo effect in that case...
I would suggest to anyone considering the chocolate pre-load, to first establish healthy diet, three months minimum time between rolls, and regular exercise and then roll to establish a base-line. Then you can experiment with single variables such as chocolate or other supplements.