"Oily skin needs no moisturiser" — a myth. Oil (sebum) and hydration are different; even oily skin can be dehydrated. "Drinking water hydrates skin" — important for health, but outer-layer moisture depends largely on barrier function.
"Moisturiser makes skin lazy" has no scientific basis. "Expensive is always better" and "natural is always safer" are also misleading — what matters is a barrier-friendly formula suited to your skin type. Consult a physician for the right choice.