I think they could get 0.1 to 1 percent increase in sales by fixing family/ screentime. It doesn't work flawlessly and a teenager is basically the same as a hacker and there are too many workarounds and it is very hard to harden either iPhone or Mac.

It also needs a kill switch. (Non parents will judge I am sure)

The device with good parental controls will be the go to for many parents regardless of practically anything else.