In this case the IBO belt is worthless and if this could be for the commonwealth then it should. Unfortunately N'dou is a tough gatekeeper and Matthew Hattons career is a con job. For this reason they choose to fight for a 'world title'.
They usually do but there no rules about it. Theres a couple of European champions who are not ranked in the top 15 by the WBC. Vincent Vuma was not in the top 15 when he faced Rhodes.