Just as you can open Word/Excel/Powerpoint files in iWork. Have you ever even used the things you're criticizing?
You can import/export to/from iWork into just about any common format.
iWork is just as much of a solution as Googe Drive/Docs. That's for dang sure. For iOS users it's even better because we have a full blown locally installed suite not totally dependent on being online.
Yes, I have used it.
No, I don't like doing another step to make up for Apple pushing their own format.