I find that it's usually those with a lifetime's experience that has the most difficulty explaining. They're so unconsciously competent (four stages of competence) that it's as natural as breathing. Return of the Jedi, where Luke under goes Jedi training. Using the force was second nature to Yoda, which was why he told Luke...Perhaps the teacher was not an especially good public speaker; many of those who understand their subject matter well and have mastered it professionally are unable to to impart it to others in an engaging and interesting and informative manner.
Erm...yeah. Very helpful instructions there, ya sawed-off runt.
Any DIY'er who has tried to lay tiles themselves knows the fustration of no being able to lay the tiles straight or even. When you watch a pro do it, it looks so easy, effortless even. Even after hands on instructions by the pro, I still couldn't lay the tiles flat. Stage 2, conscious incompetence.