Maybe I’m misunderstanding, but as shown in your link, $HOME does not conflict with the XDG Base Directory Specification. It partially relies on $HOME being defined.
Subdirs of $HOME are used as defaults. So using $HOME alone is not enough.
Also, prior to xdg dirs, applications were (many still are) storing their data under $HOME/.myapplication/.
Maybe I’m misunderstanding, but as shown in your link,
$HOMEdoes not conflict with the XDG Base Directory Specification. It partially relies on$HOMEbeing defined.Subdirs of
$HOMEare used as defaults. So using$HOMEalone is not enough. Also, prior to xdg dirs, applications were (many still are) storing their data under$HOME/.myapplication/.