Children are attached to their parents for years to learn culture. A bondage that to some extend is formed in the womb. How would dinosaurs have a 'natural' way for education when they hedge from eggs and are left to themselves? All their culture has to be encoded in DNA which most likely takes up more brain tissue and much more time to evolve.
There are breeding birds, so some form of attachment is possible. But that needs another limit. Birds need feathers before they can live on their own. Which limit could exist for dinosaurs? Crocodiles and turtles have kept on non-evolving for quite some time.
(And there is no place for sapiened birds because the head is too heavy.)
It's the other way round: hatching from eggs means being able to fend for oneself which means that they don't learn that they have to stick around.