I remember my mom using coconut oil but for tanning, not as sunscreen, the reason being because you couldn't get sunburned from using coconut oil as a replacement. I don't really know how this conspiracy theory works in non-tropical countries, but in tropical countries you'll feel like a piece of shit after a day under the sun with any kind of oil on your skin.

Its just another example of the Appeal to nature logical fallacy, like saying that the Vitamin C found in Oranges is better that the one in Vitamin C tablets/pills just because it's natural, where there's absolutely no difference under a microscope, I mean, there are micronutrients and sugars that you won't find in the pills, but the Vitamin C found in both places is exactly the same compound.