Tommy Boy,
Some users just aren't that computer literate, and they follow links on the board pasted by others, and then freak out when told they can't read because they aren't a member. They never look and see that they just need to log in to the "other" domain, they just fire off an email "Why did you ban me?! I can't access the site!". Users are generally paranoid people. This hack just might save the sanity of some poor webmaster somewhere.
Amy