What makes Word the best tool for serious writing? I use Pages for writing papers (for humanities courses) and vim+pandoc for math. I have dabbled with Word here and there over the years but I've never seen anything that would indicate to me that it's amazing for writing. Personally, I can't figure out what's going on with the ribbon. It just seems to be a heavily modal interface which is not particularly discoverable.
I've also dabbled with Pages lately, and I don't think I've found any features for now that I desperately miss from Word. Now granted, this is just my workflow, which I believe is fairly basic. But the thing is, most people's workflows are basic. I'm gonna guess that about 80% of people wouldn't miss anything by switching from Word to Pages.
It's a typical example of collaboration lock-in that you'll encounter in so many other areas. It's the reason why so many people are forced to use Adobe apps or Visual Studio.
The most important feature of Word is that everyone has it.
But nothing about that applies to the writing process itself. You could be like George RR Martin and write in WordStar for DOS and then convert the files over to Word before you send to your editor. The main issue there is how often you need to correspond (which may be seldom for a novelist like Martin).
Because otherwise, I have zero idea what that sentence was supposed to imply. If "serious writing" actually means "typing words in a serious manner" in the original comment, then I don't really have much to say, except that OC is probably spewing utter nonsense.
Since a free iCloud account gives you access to the online version of Pages, collaboration with others seems to be covered, including simultaneous editing.
I used to use Word and I'll sometimes use it if I need to if that's what a publisher is using but I never really loved the ribbon and there's way too much clutter that I never use.