There's actually a very clear scientific reason, coconut oil has the highest percentage of medium-chain triglycerides (MCTs) of any oil, and what do the p.acnes bacteria feed on? MCTs. Coconut is the number one thing I must avoid or severely limit to stay clear. It's at the very top of my evil list and by some distance. But I think it's all down to what causes your acne. I have self-diagnosed and know 100% that my acne is caused by gut permeability and malabsorption. So when I consume MCT oils and they make it into my intestines, they seep out and are taken up by my blood and expelled through the skin, where the p.acnes have a field day multiplying and feeding. I've never read this connection being made anywhere, I discovered a few years back that coconut absolutely positively makes me breakout guaranteed, and when I looked into why, I found out that p.ances feed on the stuff, but I've yet to read anybody else anywhere make the connection.