Given the subtle and surprising interactions between use-keyboxd and the various --*keyring options (see discussion in T7265), several downstream distributors of GnuPG are reluctant to enable use-keyboxd by default even for new installs.
For example, some documentation might describe commands that use a --*keyring option, and those commands would then behave differently for different users -- even those running the same version of gpg -- depending on when the user's ~/.gnupg homdir was set up.
This is currently the case for at least Ubuntu and Debian, for what it's worth. The patch for disabling this behavior is attached here.