>MS Office has officially supported ODT for years. [...], or are is MS's ODT support incredibly buggy or what? The bugs of programs trying to read others' file

>MS Office has officially supported ODT for years. [...], or are is MS's ODT support incredibly buggy or what? The bugs of programs trying to read others' file formats goes both ways. LibreOffice has problems reading some *.docx files -- and likewise -- Microsoft Word has problems reading some *.odt files. Example thread of trying to keep "tracked changes" preserved in .odt files when co-workers open it in MS Word: https://forum.openoffice.org/en/forum/viewtopic.php?t=99962 https://forum.openoffice.org/en/forum/viewtopic.php?t=99962 That type of interoperability issue also happen with *.xlsx and *.ods spreadsheets that have non-trivial formatting or advanced functionality. The advice of "just use the OpenDocument format" is not that simple because round-trip fidelity of the file may not be 100% preserved depending on what features of the software the collaborators use.