Earlier quoted context omitted.
It could simply be that no one else has implemented those open standards. Apple isn't responsible for adding support to other platforms, so it's technically accurate if the standards are indeed open, regardless of whether other people have chosen to implement them.
So why do people go after Microsoft when one can save to .docx format which is based on a real open standard
docx:
* Is horrifically complicated.
* Is not likely to ever be completely implemented by any third party.
* Does not accurately describe the behavior of MS Office.
* Was rammed through the standards process in a way that demonstrated partisanship more than technical merit.
Whereas this offering by Apple does not seem to exhibit any of those properties.