Often this comes down to the ability to communicate, work with people, and understanding real world business. In addition, often the more simple a learning method used the better. I actually find most businesses needs can be solved by straightforward analytical methods such as traditional statistics. Very few situations require actual machine learning and it is often misapplied.

In fact, having a PhD does not tell you a whole lot about these skills.

More advanced modern techniques such as deep neural networks, reinforcement learning, etc.. are all extremely proficient at certain niche problems but these do not come up nearly as often in a business context.

This is why I don't advertise myself as a machine learning engineer. Rather, I am a business consultant that knows when, and when not to utilize machine learning methods.