As a Personal Trainer myself, I agree with some portions of the article. For instance, setting goals to get you to workout and working out with friends for motivation and fun challenges.
But to say that it's not good to start with a Personal Trainer to figure out what activity works best for you I think is wrong. If you start off with a good trainer (I mean one that has been in the industry for years, not someone that is just out of school and is eager to train someone in sports conditioning) you would get a full evaluation including asking the person about what they have done in the past for fitness, what they liked and didn't like, and what kind of workout they are looking for....from there we can suggest classes to take, if they are part of a gym or suggest outside activities that won't seem like a workout if they enjoy the outdoors. Not only that we can help the person figure out their physical strengths and weakness to let them know what they can do to improve that in the activity they would like to do. Trainers are there to help with direction, to assist the person to right activity that will motivate them to make fitness a part of their life.
You'll know those who are new to the industry because those trainers won't give you options and they will suggest what you should do WITH THEM just to get you to buy sessions. A GREAT TRAINER will look out for your well being by providing options to help you get fit and into a healthier lifestyle. Those are the trainers that actually LISTEN to you when you talk, not the ones who hear only dollar signs. A GREAT TRAINER will do research for you about what ever it is you need i.e.; physical therapist, nutritionist, exercise class, etc., even if you never trained with them before but you know them for a while either through your local gym or through a friend that trains with them. GREAT TRAINERS can help someone get into a lifestyle choice by providing options because they (should) have endless business contacts in the fitness world to help someone go in the right direction that will work for them EVEN if they don't work with a trainer in the end.
I believe that when one becomes a personal trainer, it's almost like they need to help those who are struggling to find they way to a healthier lifestyle. We have the knowledge and the contacts. We should be able to share that without looking to receive money in return.