Why use Libre Office on a Mac when Pages, Numbers and Keynote are free (as in beer)? I’m going to go out on a limb and make a baseless argument that the Libre Office install base on the Mac is very low. On iOS it’s non-existent.
On iOS, dunno, you probably have a point there.
It doesn't have the features you need when you're creating more complex documents. Last time I've used it it didn't even allow you to have different sections which allow you switch between the rotation of pages.