Difficult to say without an example, but "code isn't enough" is just one possible conclusion in this case. Another one could be that the code is not actually as good as expected, and another one is that the colleagues may need to... do something about it.

An obvious example I have is CMake. I have seen so many people complaining about CMake being incomprehensible, refactoring it to make it terrible, even wrapping it in Makefiles (and then wrapping that in Dockerfiles). But the problem wasn't the original CMakeLists or a lack of comments in it. The problem was that those developers had absolutely no clue about how CMake works, and felt like they should spend a few hours modifying it instead of spending a few hours understanding it.

However, I do agree that sometimes there is a need for a comment because something is genuinely tricky. But that is rare enough that I call it "a comment" and not "literate programming".