What are some of the disadvantages of the Igbo culture's social structure in Things Fall Apart?

In Chinua Achebe’s Things Fall Apart, one of the major disadvantages inherent with the traditional Igbo culture’s social structure can be found in the tribe’s treatment of undesirables and outcasts, or osu. Osu are unable to climb up the rungs of society in the same way that Okonkwo and others can; indeed, the Igbo of Umuofia enforce a kind of caste system:

"He was a person dedicated to a god, a thing set apart-- a taboo for ever, and his children after him. He could neither marry nor be married by the free-born. He was in fact an outcast, living in a special area of the village.... Wherever he went he carried with him the mark of his forbidden caste-- long, tangled and dirty hair. A razor was taboo to him. An osu could not attend an assembly of the free-born, and they, in turn, could not shelter under his roof. He could not take any of the four titles of the clan, and  when he died he was buried by his kind in the Evil Forest" (156).

The clan’s maltreatment of osu creates a powerful recruiting opportunity for the incipient Christian missionaries in the region, and they increase their numbers by incorporating osu into the church.

Another notable disadvantage in the Igbo’s social structure comes in the form of their strict punishment system. Okonkwo is himself a victim of a seemingly arbitrary sentence when he is exiled from Umuofia for seven years for inadvertently killing a young member of the tribe. Obierika questions these traditions after Okonkwo is punished:

“When the will of the goddess had been done, he sat down in his obi and mourned his friend's calamity. Why should a man suffer so grievously for an offense he had committed inadvertently? But although he thought for a long time he found no answer. He was merely led into greater complexities. He remembered his wife's twin children, whom he had thrown away. What crime had they committed? The Earth had decreed that they were an offense on the land and must be destroyed” (125).

Obierika questions how these traditions actively benefit the clan, especially when they seem to actually hurt those that surround him.

These are a few examples of how the rigid traditions of the Igbo culture can be problematic to members of the clan. Osu and Okonkwo alike suffer due to the social structures that are firmly upheld by the tribe in Umuofia.