Useless documentation means half-arsed is better.
The world of IT is broken, what sort of idiot gives Linux to their parents when as a trained developer man is so useless?
It's just excuse after excuse. Unit tests are documentation sort of garbage.
That's what's mind blowing about LLMs, IT devs are so bad LLMs are better. Hacker News comments also confirm this.
If the audience is teammates, the _code_ itself is usually the best documentation.
Tests lie about edge cases. A test _might_ be demonstrating an edge case, or the suite might ignore large sections of edge cases.
Documentation is worse, it rarely documents edge cases. Country Y passes legislation and you need to implement it? Yeah, the docs aren't getting updated.
If your audience is a different team, API references (the headers/RPC message schema/javadoc/etc.) are better than written docs. Again, they are less likely to mislead you and are much more likely to work.
Unless, of course, the interfaces are telling fibs about what is allowed. Interfaces that are big buckets of parameters can do that.
Only if your audience is an external organization would documentation be a good primary reference. It meets them where they are, selling them on the capabilities of the software and bootstrapping them to the code.