Some parks do do this, but to the best of my knowledge neither US Disney resorts do.
Even at parks that do, the ride ops on the scene make the ultimate call, and I have seen kids with wristbands turned away because they weren't even close. Unfortunately, some parents will move wristbands from one kid to another in an attempt to get Junior on the big rollercoaster...
Having two height-challenged but not thrill-challenged children, we just tell our kids in advance to expect that they will not be able to ride things that they are close on, but they are welcome to see how much they've grown when we get there. That usually solves most of the disappointment.