I´ve learned in life that you can generate a better solution by asking others what they think before coming up with your own solution - doing so is a sign of maturity, and in professional life willingness to gather data in that way often indicates leadership capability..
In general, I have to agree. Why reinvent the wheel if somebody else has done it already?
But in this case the QXC (or indeed most everything else in the PPL course) is not aimed at finding the most efficient or cost-effective QXC. The intention of the QXC is a learning experience and a confidence builder. The more you figure out (correctly) for yourself, instead of asking others, the more effective the QXC becomes.