Compulsory & Optional gymnastics are different animals. A good compulsory gymnast does not always translate to a good optional. Just to add a child can have a so-so compulsory career and excel at optionals.
I do believe that compulsory is where you learn & should master your basics. Strong basics and strong conditioned bodies lead to easily learned higher level skills.
I really disagree with the first paragraph of the article. The skills you learn in compulsory on bars do translate to the higher levels. Now I'm not talking under L4 and honestly even L4 bars are useless, but L5 & L6 bars are very important and I think it is clear to see when you watch the higher levels. L5 is the kip, the squat on and the tap swing for dismount - all used in higher levels. L6 also has the flyaway & the clear hip. All of these skills are the basic foundation of the higher levels.
Without a great tap swing, you will not have beautiful giants, you will have archy backs and no flow, you can see a struggling giant and I would bet that you would see at least a handful of struggling giants in the higher levels at a meet - hopefully not too many, but you always see it. Without a good tap swing you will not have a good dismount.
Now I just focused on 1 part of what the guy wrote, the rest of what he said is personal preference. If you don't want to do USAG compuslories, then go the route of USAIGC. If you don't want to do any compulsories and only focus on optionals, then go find a gym that works that way (I think you will have a hard time finding.)
Our country is results based, we want to see results for hard work and our spent money. I think that is even more evident by the fact that now they have L1, L2 & L3 and are actually competing them, giving awards, charging you to come see your child compete and you have to pay to register to get a number to go to these competitions, besides buying a comp leo to wear. It's what the majority of people seem to want, it seems to be mainstream these days. At this rate, we will probably have some type of pre-team competition in due time, because we can't go lower that L1.
USAG is basically a league, just like AAU, USAIGC and the likes. You can criticize it, but if you don't like it, don't use it. It's just one way to obtain your goals.
You can have some guy write an article about how compulsories are not necessary and list all of his gymnastics accomplishments, but it's not rocket science to figure that out. The thing is that USAG is probably the biggest system in our country so it's used by the most people and is the most common means of meeting those goals, but no one will argue that it is the only way.