then... it won't work? Alternatively, you could make it group writable by yourself and whatever the webserver is running as. Or, if you are using suPHP (http://www.suphp.org/Home.html), you won't need to chmod anything.
I agree with the logic, how much trust should I place in software when the documentation says "setting up groups and permissions would take 30 seconds of thought and a minute or so in total. That's too hard for me so fuck it, just do this horrible thing to turn off security completely". Did they handle other problems that way too?