Mark, what qualifications do you even have? Did you take that out of a bad magazine or something?
If you have acne and don't wash your face, you will notice a difference if you suddenly do wash your face. Washing your face in a hard fashion is poor hygiene, actually. That alone can cause injury. Acne is an infection. It is like a wound, like a small scratch or paper cut. When you get a small scratch or paper cut, fail to clean it out and some small particle such as of dirt remains in this wound, it likely shall become infected, like a pimple. The issue of natural oils resulting in acne is that it provides a nice environment for bacteria, which can also cause infections.
Different foods sometimes make a difference in the homeostasis of someone's body. Food doesn't directly cause acne, but it may contribute to extending its effects.
Stress does help promote acne. It screws with you body's balances, particularly that of hormones. The stress you're obviously referring to is the regular day-to-day stresses, as you say, but stress in relation to acne is typically referring to periods of higher stress, such as examinations, a higher workload than normal, deaths in the family, diseases, etc. These stresses can help weaken your body and make you more susceptible to infections and diseases ini general.
Acne is not a disease, in the first place. It's just a problem. I don't even know who would believe that acne would be purely cosmetic. If you're concerned about acne, it is obvious that it reaches further than just cosmetically speaking.
Not all acne can be cleared up, and not everyone has the money that would be able to clear them up. I know I don't have the money to see a dermatologist. And what about the reason of genetics? My mother is 46 years of age and still gets a pimple or zit every once and a while. If you have the cure all for everyone, which would have to be the case for you to make such an assertion, why don't you let us all know about it?