I use iWork for everything I do, so I don't think its impossible to do so, but iWork is missing (especially iWork 2013/14/15) numerous features that office has.
The reason why iWork has gone so far backwards for full iOS compatibility - so that any feature seems to have to be added on iOS and OSX.
I'm one of those people who use older versions of Apple software. I used iMovie 6 HD for a while after iWork 08, and i'm currently using iPhoto because Apple couldn't be bothered to include numbers iPhoto features and organisation methods into Photos. I know a lot of people are using the Final Cut Pro before Final Cut Pro X came out.
In terms of iWork, I wish they'd made iWork 09 into the pro version and charged for it and updated it continually as a full Office Competitor, then the normal iWork would just be free and the same as now. Wish they'd done the same with iPhoto and made it Photos Pro.
The other approach they might have taken is including compatibility modes for the earlier and iOS/iCloud versions of the apps. Instantly stripping formatting out of documents created in the previous versions of Pages when they are opened in the latest version and without any warning was the worst possible solution. It's a thumb in the eye to the existing user base and just so unnecessary.
As for document sharing using the "compatible standard" Word format, this is mainly an illusion. The two platforms and many versions of Word all but insure that shared Word files aren't going to look the same to everyone who opens them. This is okay because in reality very few documents are going to be truly "collaborative" in their preparation because someone on the writing team should be responsible for the final report production. This should be someone who understands document formatting (a tiny percentage of the user population if the documents I see are any guide). The final version should be a stable, un-editable, and universally viewable PDF.