Teaching your child to never say “no” to an authority is not preparing them for adulthood. At all. Instead, it prepares them to fall into patterns of abuse or dysfunction. It prepares them to obey an unreasonable or abusive boss rather than going to HR or quitting and finding another job. And so forth. Children need to know that they can say “no” to those in authority over them, both as children and, in the future, as adults. 

In the present, before they grow up, teaching children not to say “no” to an adult makes them perfect targets for abusers. A child who has been taught never—ever—to say “no” to an adult is laid open and ready for grooming and abuse. Children very badly need to know that they can say “no” to adults.
He had been a military man before being given this job as a kind of pension, and that was a bad thing in a senior copper. It meant he looked to Authority for orders, and obeyed them, whereas Vimes found it better to look to Authority for orders and then filter those orders through a fine mesh of common sense, adding a generous scoop of creative misunderstanding and maybe even incipient deafness if circumstances demanded, because Authority rarely descended to street level
—  Night Watch, Terry Pratchett, p. 72