One of the founding principles of the (CFA, African Financial Community) was that colonies had to keep 50 percent of their foreign currency reserves in the French Treasury, plus an additional 20 percent for financial liabilities. Thus, member states only retained 30 percent of reserves within their borders.
The monetary zone limits industrialization and economic development and discourages trade among member states
Just look up their colonial past. Before you think “That’s old stuff now”, some places still suffer from French colonialism today