Oil does cause acne. Acne happens when excess skin oil (sebum) on the face is mixed with bacteria and dead skin cells and clogs the pores...what else would cause the acne? Excessively drying the skin through products won't help acne either though but will likely cause acne formation to become less recurrent. Highly dry skin can cause acne as well...

Oil is the main cause of a clogged pore internally yes. But I think what AMRoup tried to say was external oil for skin treatment,which none the less can be essential for healing the skin.
Using tea tree oil, lavendel oil, frankincense oil etc. are all 100% skinfriendly and proven to actually heal scarring.
I even know various doctors who agree with me on this as well.