There's all kinds of reasons that this isn't sufficient, return based pricing, multiple seat pricing bands for a single flight (for some airlines this is dynami

There's all kinds of reasons that this isn't sufficient, return based pricing, multiple seat pricing bands for a single flight (for some airlines this is dynamically calculated on a moment-by-moment basis), airline and airports rules covering transfers for whether a given pair of flights connect or not, etc... the list is basically unlimited.