Board Thread:Support Requests - Getting Technical/@comment-997381-20160422133306/@comment-1757994-20160423001639

I think your perspective is incorrect. Interwiki transclusion is a bad thing which basically screws with the caches, which is why Wikia has not enabled it globally.

If you want an answer as to why Wikia enables it from Community, you'll need someone from Wikia to post. I suspect it's required to enable something else, like global Help: or MediaWiki: pages. Explicit interwiki transclusion is still discouraged, however.