Not only do you learn from your mistakes, but you can keep records on how long it takes a plant to germinate, how tall or wide your plant will grow or when will you recieve fruit or flowers. There are even unfortunate circumstances that you should record. Such as when you have an invasion of pest, noxious weeds or drought conditions.
You might not see yourself as a scientist, but in a sense you are a scientist. Gardening is a great science that doesn't end and can give you great outcome. When you are growing heirlooms you are preserving a species that may be endangered, growing healthy vegetables can give you the knowledge as great as any nutritionist, and having knowledge of herbs can bring knowledge that is expected of a pharmacist.