For the record, I reported this bug to Wikia back in July, here's the old forum thread I created about it. Both Brandon and DaNASCAT were not able to reproduce it at first, but after a string of email replies and that forum thread, eventually DaNASCAT saw it. So it should be already ticketed. The support request was #43403 if that helps.
How ... odd. Yeah I can only confirm that we definitely have CreatePage outright disabled by Staff. Maybe one of the reasons that this never got fixed is that no one was able to prove the source of the error.
Perhaps by submitting an error report that demonstrates that it has to do with the CreatePage dialogue box, we can actually get this puppy fixed. It's obviously a bug, and it's directly connected to CreatePage.
If it helps, the exact support request that turned off the "create a new article" flow is #21250, entitled 'Getting rid of "create a new article" flow'. Maybe that specificity will help them figure out how it was turned off, which will then lead to a quicker resolution.