Some do, others don’t. It depends on your specialisation. Photographers work with light. Some prefer natural/ambient light, some add LED/tungsten/HMI lights to their skillsets and others venture into flash photography with light modifiers.

Sometimes your assignment will not allow flash usage and you adapt. It doesn’t hurt to learn about light and how to control and shape it. Light and cameras are the tools we have to create our vision. The more you learn, the better you can adapt.

For instance, a lot of real-estate photographers shoot their house assignments with only ambient light (3–5 exposures bracketing). Some portrait photographers rely on natural light and fast lenses. Landscape photographers do most of their work without flash (there are some that are bringing portable flash units with them).

Once you start looking, you will find successful, professional photographers shooting without a flash. If you want to specialise in product photography, commercial photography in general, knowing how to use a flash is a must. Flash photography gives control and accuracy, especially with colours. With control and accuracy comes speed. You will be able to work faster in a controlled environment and clients don’t want to pay for waste/down-time.

For example, I was shooting a hotel room and the client wanted to see the sunlight coming in. It was the wrong time of the day and the wrong weather conditions (overcast day.) The solution, rig a flash outside, strong enough to simulate sunshine coming through. Flash photography puts you in control of the light and you can shape it the way you see it.