Sometimes people make an assumption that every codebase has a team (or at least a single person) devoted to maintaining it. Companies with large codebases may not be able to afford that, or don't think it's worthwhile. You could have dozens or hundreds of libraries and only a few maintainers. The libraries are effectively "done" until something comes up. Work on them is interrupt-driven.

In that situation, coming in cold to a library that you haven't worked on before to make a change is the normal case, not "cognitive debt."

If you have common coding standards that all your libraries abide by, then it's much easier to dive into a new one.

Also, being able to ask an AI questions about an unfamiliar library might actually help?