Can people who aren't technical geniuses build complex systems?

Jobs was a marketing genius. While Gates understood Microsoft's marketing plan in depth -- their approach was fundamentally different.

You can also compare Jobs to Edwin Catmull when he was running Pixar. Catmull was an analytical thinker with a background in science. Obviously Jobs complimented him nicely -- and Jobs was critical to the success of Pixar.

You need to understand the implications, context and how a technology works. But you don't have to be the best engineer in the world to build tech companies.