Just the idea that you might have this serotonin syndrome, when you're tripping can causse a very unpleasant experience. I once fell on my face during an acid trip, and the thought that it might have caused some medical trauma so maybe the very next moment i could maybe become paralized forever or become permanently blind, caused a few very stressfull minutes. So i take the food guidelines seriously just so i don't have to worry about it and it will be all much more pleasant.

This will also diminish initial feelings of nausea etc.

All these guidelines are meant to be on the safe side as much as possible, just like with warning labels on pharmaceuticals. When taking 50 aspirines would kill you, the company will warn you not to take more then 20 or something. Still a good advice i would say.