The authoring half
Word as the authoring surface, SharePoint as the substrate
SharePoint-native storage solves the IT half of the CCMS adoption problem. It does not solve the author half, and the two have to land together: the substrate decision is wasted if subject matter experts will not author in the first place.
Microsoft Word is the authoring surface that pairs naturally with it. SMEs stay in the tool they already use, the DITA structure is applied behind the scenes, and the Word add-in saves components back to SharePoint.