Why was White Fang unable to enjoy romping and playing with the other puppies? What effect did this have on him?

From the text:

He never played and gambolled about with the other puppies of the camp.  Lip-lip would not permit it.  The moment White Fang appeared near them, Lip-lip was upon him, bullying and hectoring him, or fighting with him until he had driven him away.

The effect of all this was to rob White Fang of much of his puppyhood and to make him in his comportment older than his age.  Denied the outlet, through play, of his energies, he recoiled upon himself and developed his mental processes.  He became cunning; he had idle time in which to devote himself to thoughts of trickery.