You can also open all of those documents with LibreOffice. My point is the support LibreOffice has for Office documents is fine and not at all a problem, because Office formats have not meaningfully changed over time and they have been supported in LibreOffice for all of that time.
The comission has themselves made the commitment to reduce the reliance on exactly such standards. You are arguing for a position that they themselves aren't even arguing for as they recognize the importance of the problem.
By your logic, it would have been fine for Apple to stick with the Lightning port for charging because USB->Lightning charging ports are widely available so "it's not a problem at all".
No, because Lightning is not an open standard. OOXML has been an open standard for nearly two decades.
And a big issue for me is this blog post hurts LibreOffice because the largest reason enterprises won't touch it is that it is perceived as incompatible even when that compatibility works just fine.
If success and good marketing was the focus, LibreOffice would happily promote that it will take any file format they get because they have robust interoperable software that doesn't actually mind handling XLSX!
Great, I can open proprietary document formats with proprietary software. I think you are missing the point of this "performative exercise".