If you request help for an autoloaded function that doesn't have a
doc string, the @file{*Help*} buffer won't have any doc string to
display. If @code{help-enable-symbol-autoload} is non-@code{nil},
Emacs will try to load the file the function is defined in to see
whether there's a doc string there.
https://gitlab.com/ganserla/emacs/-/commit/c53aff5de71d7c558c222c35fd1cda0298d834b1