It is true that traditional editorial structures don’t exist in Nigeria. In the West, a brilliant author could submit their manuscript (through an agent) to a publishing house and find themselves assigned to a brilliant editor. Together, the author and the editor would work to make the manuscript shine. This would take months of bickering and rewriting. It would be hard and it would be painful – for both parties – but in the end the final book would be the best book it could be. In Nigeria, most publishing houses are no better than one-man operators with printing presses. Those that aren't are under enormous pressure, and often can’t afford the time or the cost of an in-house editor. A writer looking for important editorial feedback doesn't have a lot of places to go.
However, I think the bigger problem is the attitude of many writers themselves. Too many Nigerian authors are going into the world of letters with dreams of instant stardom. For them, it is more important to see their book published than to make sure it is a quality product. They are approaching writing the same way one would approach the selling of second-hand shoes – with an eye to quick profits and a big launch with lots of deep-pocket donors. They have no desire to go through the pain and hassle of a thorough editorial process.