Any marketable skill, no matter how advanced or niche, is built on a foundation of simpler skills. Seen differently, successfully executing any skill is directly dependent on your ability to execute the simpler ones.
Let's try an example.
Jeff Atwood says that programmers are typists first, programmers second, and I agree with this. If your job is to type on a keyboard and write code, then you damn well better be a great typist, because if you type slowly, you code slowly. And if you code slowly, you're not a good programmer.
The marksman learns how to properly hold a rifle. The martial artist masters the movements involved in every kick. The chef can cut an onion in her sleep. The musician has the layout of their instrument memorized.
If you can't do the boring things, if you get slowed down on the basics, how can you possibly be exceptional at what actually matters?