Yes, AD is the value proposition. Your employees can get cloud-synced, multi-user real-time editing of documents. This is what kills the "but my Linux app can do it for free."

It runs on-premise, has all kinds of certificates and has a history of half a cenutry (give or take.) That kills Google Docs.

It's cross-paltform, killing whatever Apple thinks it has.

Too many people think Word is a text editor. I'd use Notepad++ if it had full AD integration. But it doesnt.