Yep, this is a product from Eastern Europe, our public institutions have decades worth of files in Microsoft's formats that we still work with on daily basis and that nobody will ever rewrite from scratch. It's not necessary to support every new feature, but opening stuff from 2000s and 2010s and saving it without compatibility issues is like mandatory if you want to ship an office application here. It's understandable that a company targeting our local markets prioritized OOXML and not ODF. I do hope the Western fork puts more effort into the open format now though.

The format that's being used is the proprietary one whatever MS is calling their office nowadays shits out not the actual ooxml standard. This is just going to reinforce MS propaganda that alternatives are inferior when the office suit fails to properly open files on it's own preferred format.

Sure but ODF support doesn't conflict with that, by all means they should attempt MS compatibility while it's still so dominant, but not supporting ODF is a choice that will only ensure things will never change.