The best coaches are not necessarily the best players.
Like in sport, coaches are good at pointing to particular aspects of someone's game, but were not necessarily great at putting it all together on the field. You find there's different coaches for attacking, defending, etc.
They all tend to have tried playing at some level, however. Even Mourinho was a senior player for a short while.
I suspect programming gurus are no different. They may get very good at shouting RAII or SFINAE at you, without being great at executing it in a large project.
Like in sport, coaches are good at pointing to particular aspects of someone's game, but were not necessarily great at putting it all together on the field. You find there's different coaches for attacking, defending, etc.
They all tend to have tried playing at some level, however. Even Mourinho was a senior player for a short while.
I suspect programming gurus are no different. They may get very good at shouting RAII or SFINAE at you, without being great at executing it in a large project.