True in case you needed the CPLD in your application and had a pair of pins and some gates unused, or you used 2 MCUs from which one has to be a "real time" one and the other can perform its tasks with some delays and can take up such a "real time" task, then it's obvious there's no need to add an extra chip when all can be done in the existing hardware. But if the hardware is to be dedicated for the task (like in this particular case), it makes no sense to employ CPLD or MCU where a generic chip dedicated for the task suffices.