Steroid use has been shown to increase muscle in untrained males by around 25-30% I believe, without adding any exercise. That doesn't accomplish too much. If you want any worthwhile results, you will still have to train, although the steroids produce significantly more results for the same investment.

Andre the Giant said he never worked out, he just wrestled. He had some kind of growth hormone disorder, if I recall.

Think about gorillas, who are pretty similar to us - they don't lift weights in the gym, do they?