Board Thread:General Discussion/@comment-168424-20150910163231/@comment-168424-20150910191141

Summarized answer: Much of the reason for the divergence between WMF and Wikia code is due to different needs between WMF and Wikia. The shared and different functionality is handled on a case by case basis. Wikipedia wikis are more limited in scope and more vertical, whereas Wikia is more horizontal and has different issues of scale.