Big scam, they are ignorant and make a lot of money from these things.
A person gets crooked teeth due to poor oral posture (caused by improper breathing and a bad (weak/soft) diet (bad swallowing and chewing as well)). Instead of helping the patient by expanding the palate, they instead chose to extract your teeth and move your teeth around to give you a straight smile. There is plenty of evidence from the skulls of natives just a generation ago with perfect jaws and healthily teeth that environmental factors are the cause of bad teeth (diet/posture).
I am kinda annoyed I had my wisdom teeth extracted when I was a teenager, because it "might have grown crooked". I feel bad for those who had more extractions done to get braces, luckily for me I always enjoyed chomping and whole carrots and apples so I did have some degree of hard foods to promote proper facial growth so my teeth weren't crooked enough for braces.
The only time you should get teeth extracted is if you have a rotten tooth or infection, and you can always get a false tooth replacement.