Think of the last time you were part of a group photograph. It might be quite some time ago because selfies have become very popular, but try to remember the feeling of asking a stranger to hold your phone or camera while you stand with your family or a large group of friends.
That stranger is now responsible for the quality of your photograph. If you are lucky, they understand lighting, angles, composition, and the rule of thirds. They know how to focus your camera or adjust the flash of your phone. If they don’t understand these things, which is likely, you are just plain out of luck. Your photo might be blurry or poorly lit. If someone is blinking at the wrong time you won’t know until it is too late. The person taking the photograph doesn’t know what they are doing and although everyone in the photo looks great, the photo itself does a poor job of showing it.
This principle is why product photography exists. If you want to sell your product online, you will need a picture of it. The person who takes the picture is almost as important as what is being photographed. The photographer understands how to portray the product in the best way possible. We don’t recommend hiring a professional photographer for a casual dinner with your family, but if you intend to sell something online your smartphone might not be the best option.