We have finally come to see through science and research that eating one food the rest of your life would not be healthy- no matter how healthy that single food is. The body requires a varied diet.
Your skin also requires a varied diet to function well. When we break down the fatty acid content of oils and butters, we see that they are each unique. All oils contain different sterols, vitamins, and minerals and at varying levels.
This is exactly like breaking down food and seeing that no one food has all the variant nutrients that our bodies require to reach their full potential for health.
This is why my blends include both oils and butters and this is why I never recommend the use of a single oil for skincare- unless it's because we have yet to pinpoint what is causing an allergy.
I cannot count the number of new clients who have come to me with skin problems BECAUSE they were using just ONE oil to moisturize or cleanse with. This would be like going to a nutritionist and telling them you're frustrated that your body isn't healthy but ALL you've been eating is one single food. No one vegetable is good enough to live on solely and no one oil is great enough to use every day with nothing else.
Also, when we use oils and butters synergistically, we maximize their effect on our skin. You can use just one carrier oil that is known to assist with acne, or you can provide the skin 5 oils that are known to clear acne. Think of this as a well-balanced meal for the skin.
I don't believe that there is a "perfect" single oil out there to moisturize or cleanse the skin. I do believe that nature has given us a myriad of sources and those sources also change with the seasons. It can be important to look at changing your skin care from summer to winter just as our ancestors would have been changing both their diets and their body care regimens at these times as well.