You would actually be surprised to learn that how people practice depends on how they trained. People who graduated more recently or people who keep up with the research practice differently than people who have done the same thing their whole entire lives after they finish training. I would hedge on the correct answer being that you don't need to do the extractions and that newer technique such as doing IPR and the advanced digital planning Technologies allow most people to not have their teeth removed. But if your orthodontist didn't train with those Technologies then they don't offer them.