I think the article has a point and yet misses the point. If you start a company and don't have investors that can fire you, it is true you still don't work for yourself but for your clients, employees, etc.

Nonetheless there is a huge difference in that the ability to terminate a relationship with a boss is possible from either side, without you losing your position in your company. It's wonderful being able to tell a client that if they are going to micromanage you, they can take a hike.