I'm old enough to remember this happening: https://en.wikipedia.org/wiki/Standardization_of_Office_Open...
Basically, Microsoft furiously bribed their way into formally standardizing the utterly broken MS Office formats, so EU and potentially other regulators couldn't mandate them to be "interoperable" with existing standards (e.g. OpenDocument, based on OpenOffice, which was on its normal way to become standardized with no fast tracking and no bribing). They even called it "Office Open" to foster confusion.
They can do whatever they want and get away with it because a big part of their business model is, much like Oracle and SAP, based on bribing government bodies across the world.