We can see that people are all different on the outside, it stands to reason that we are also all different and unique on the inside. So does that not mean that teachings and spiritual goals should also be different and unique? Perhaps what works for one person as a path will not work for another.
You could say that this is the individual’s responsibility, but what does it mean for the student-teacher relationship? How can a teacher guide you when your experience could be very different from his own? More so, why has no-one tried to survey inner uniqueness and it’s effects on teaching (spiritual or normal education).