Office formats have also, as mentioned in the source link, been an open standard for fifteen years. It may not be the better open standard, but it is an open standard, and it works fine, including with LibreOffice's software, for many years.

This is like if Google was whining someone sent them a JPG instead of a WebP. Not invented here syndrome more than an actual openness complaint.

It's also stupid and self-defeating: The top reason people disregard LibreOffice as an option at work is because people believe it's incompatible with the Office everyone else uses. And it's NOT! But if LibreOffice itself keeps promoting misinformation about its own software, it's going to continue to be obscure in business.

LibreOffice is better software and deserves better marketing than this incredibly dumb claim made above.