Although parents should gently set limits, punitive discipline for very young children and babies is repressive and can quash exploration and excitement in the first two years of life. It will be interesting to see some follow up on these kids in later years. I suspect that they'll have a lot of inner rebellion."
This is similar to what they teach in the PET program (creator Dr Thomas Gordon was even nominated for the Nobel Peace Prize) that the authoritarian style of parenting may produce obedient, well behaved children. BUT they WILL eventually break out. They will get to the point of rebellion and have little or less respect for their parents and not seek them out for as much advice or help. They wont come to them with problems as they fear an authoritarian response and may feel resentful, angry, frustrated and repressed. Instead PET recommends an authoritative approach which I have to say has worked wonders in this family.

This thread and this thread are a good read.