> if someone can't write clear, clean, and understandable code, why does anyone expect them to be able to write clear, clean, and understandable English (or whatever language)?
The comments don't say the same thing as the code. In the comments, the author might tell us - albeit not clearly or in proper English, what they want to achieve, or why they're doing it this way.
If someone takes a dozen lines of convoluted code to express what can be done in 2-3 lines concisely, the explanation isn't going to help. Think of the worst mess of if/then/else clauses you've seen, or someone who switches on a type instead of using polymorphism. Even if they can explain it well enough that you can follow it, the comments aren't going to improve the understanding much. They are more likely to add cognitive load and make it harder to grasp the intent.
