- π³πΏNew Zealand quietone
As much as we strive for documentation to be complete and up to date, it rarely is. It is more of an evolutionary process, fixing things as we go along. If this is referring to the Drupal 7 Form API reference, then it is a won't fix because Drupal 7 is end of life. And, if not, there have been a lot of documentation fixes in core in the past 10 years.
Closing as outdated. If you disagree, re-open an state what should be done.