[IshKebab]

He meant that people usually have cars that they need to run well. They just pay someone else to take care of it.

Similarly people usually have computers that they want to run programs on. They don't write them themselves though - they pay someone else to take care of it.

People don't commonly need brain surgery. It wouldn't really be a useful skill unless it is your full-time job.

Anyway I don't think you need an analogy to reason about this.