Two different jobs, two different tools.
Word is a delivery tool. It is where a finished manuscript gets its standard format, its track-changes edit pass, and its final shape before it goes out. For that, it is the industry standard and nothing here changes that.
DraftProse is a drafting tool. It is where the book gets built and rebuilt over months: scenes moved, chapters reordered, a character followed across a hundred pages. When the draft is done, you export to Word for the last mile. The two are not really rivals so much as different ends of the same process.