Things fell apart...

In chapter thirteen of Chinua Achebe's "Things Fall Apart", things really do fall apart. In a sudden flash, Okonkwo's life has been ruined for at least seven years. But what is intriguing is the reaction of Okonkwo's friend, Obierika. Obierika is saddened by Okonkwo's situation, and yet he can do nothing but follow the customs of their culture and help kick out Okonkwo. After Okonkwo has been kicked out, Obierika goes to his obi and "Mourns his friend's calamity." He then begins to wonder why the customs are in place, and certain rules must be followed. He then concludes that if certain rules are not followed and leniency is allowed, the Gods will be angered. Why is Okonkwo's society so strict and unmoving? How is it that a man so accomplished can be punished so harshly for one mistake?