MS Word is used by a large number of professionals who are not technical writers. This installed base, that has a comfort with using MS Word, can be leveraged to promote use of topic oriented writing for the creation of technical information content.
It can be argued that the usability MS Word in a class all by itself. The reason for this is Microsoft’s commitment to evolve a word processing program that combines the availability of many features that increases productivity without bearding a user with requirements to use them.