I think we're quibbling over apples and oranges.
Some people write books and need complex indexing tools and such that only the top products like Word provide but the vast majority just use Word for a couple of pages which alternatives handle easily.
Similarly with Excel there are power users that do some insanely crazy stuff, I've seen it, that no other product in the world can possibly touch. Yet again, the vast majority just do simple business plans and balance sheets that the alternatives handle easily as well.
Remember, to nuke the MS Office hold on the world you only have to remove the masses that never needed the full power of the product in the first place and the MS empire is suddenly toast because the power users alone couldn't support the product and unless I'm mistaken wouldn't provide a big enough business case to continue it's development.
IMO it's Powerpoint that's the tool harder to wean people off as it's used a lot and is the best of breed.