I suspect that, with the exception of the truly mentally handicapped, there's nobody that's literally not smart enough to produce good, solid working software.

I suspect that, with the exception of the truly mentally handicapped, there's nobody that's literally not smart enough to produce good, solid working software. There are, however, people who give up because there's so much that you have to not just learn, but truly internalize. I'm smart enough to solve calculus problems, but not smart enough to make revolutionary advances in the field of mathematics. Similarly, I probably won't invent the next PageRank, but there's plenty of room for people who can study the techniques, grind through the examples and apply them.