Last modified: 2012-02-01 16:40:38 UTC
In the supposed case that the code in such pages could be someway active, they will affect other people using that IP/name in the future. And if they're not, it's nonsensical to allow their creation anyway. Furthermore, those subpages are not editable by non-bureaucrat patrollers, i.e. for including a {{db}} template.
This should done on-wiki with [[mw:Extension:Title_Blacklist]].