Microsoft’s messaging on the subject hasn’t done it any favors, either. Its end-of-support page for Office 2019 for Mac, originally posted in October 2023, once told owners to “Rest assured that all your Office 2019 apps will continue to function.” A revision now dated May 15, 2026 has dropped that line, replacing it with a note that their data “can be accessed in a supported Microsoft 365 or Office product.”
They could have supported both by default.
Someone somewhere made the decision to concentrate on OOXML to the exclusion of everything else, either clueless as to how that would look, or hoping that few people would notice and the fall-out would be minimal.
Either way, neglect of the open alternative is not a good look.