It is a common tactic among abusive parents to convince their child without them, they'd be unable to survive in the wider world. Any mistakes will become irrefutable proof thereof, and any attempts to break this control and do things on their own will be treated as ingratitude, often prompting the abuser to instantly abandon all parental duties to "teach a lesson".
Uh huh. And some kids haven't got their head straight after puberty at 16, and still need (or would have needed) the training wheels. Blaming it on their parents would seem unfair.
Society works on averages. Most people being ready little adults at 16 doesn't mean everyone is.
Edit: yeah, look at the downvotes. How are you all doing with that self-regulation?
I don't disagree, but in this context I don't think those are the same parents that are yeeting their kids off to board at university as soon as they are of age.