In the end? When they bribed the ISO into making OOXML a standard, what Office actually saved was incompatible with that standard on day one.
OOXML becoming an ISO standard was entirely to undermine the development of OpenDocument as an open standard. If they hadn't done that, governments asking for open standards might have required OpenDocument. Now, since OOXML is an open standard, they're immune from that even if they never bothered to implement that standard correctly.
Please place the Aperture Science Edible Companion Cube into the consumption receptacle for immediate destruction. Rest assured that the Aperture Science Edible Companion Cube cannot feel pain. Please disregard any screams you may or may not hear.