The XDG defaults put them all (per category like config/data/cache) inside one 'typically hidden' directory, how is that not better?
You're also making an assumption that the alternative is $HOME/.appconfig, which it might be, but that's not any particular standard. It might just as well end up $HOME/app.config or $HOME/Library/Application Support/MacOs/Resources/App.app/config/Config/Resources/config.
You're also making an assumption that the alternative is $HOME/.appconfig, which it might be, but that's not any particular standard. It might just as well end up $HOME/app.config or $HOME/Library/Application Support/MacOs/Resources/App.app/config/Config/Resources/config.