Ubuntu, Linux Mint, and the Guest Account

I know there's not much new here, but I am amazed that Ubuntu, Linux
Mint and friends ship with a Guest account present and enabled.

The Guest account is surreptitiously added through a lightdm
configuration file, and is not part of the standard user database.
Because its not part of the standard user database, it can't be
disabled through /etc/shadow, nor disable it through familiar tools
such as userdel and usermod. Additionally, the damn account does not
show up in distribution provided tools such as User Accounts applet.