> ... they didn't understand the machine code that the compiler was writing ...

This is a bold assumption and inconsistent with my knowledge of history. High level languages allowed better management of complexity and reduction of tedium. The common complaint was that compilers produced less efficient (slower and/or larger) code, not that the output was more complex. It was[1] normal to read the compiler's output, which was generally assembly or another intermediate representation. After all, a compiler is merely a tool for translation from one language to another. Additionally, early compilers often were not optimizing compilers; the code they generated was simpler than handwritten programs.

1: And still is, for some of us!