It used to be that the .doc format changed incompatibly with every release and if you had to share documents with someone on an earlier version you had to manually select the format on the "save as" screen. I have distinct memories of opening a Word 97 doc in Word 95 and seeing a bunch of weird boxes between each character - in retrospect, obviously because they changed the internal format from some 8-bit encoding to UTF-16.
But I can see how the conflicting requirements to keep the upgrade treadmill rolling and never break any old apps have made certain versions of Windows into such unholy piles of kludges.
the .doc format changed incompatibly with every release
Pre-XML the .doc format was just the in-memory representation of the document serialised to disk and loading it was the converse. Conceptually you could imagine it like mmap(). It was different between versions because the code was different, not by any deliberate effort.
I'm not very sure about Word, but Excel 97 onwards, Excel's story around forward and backward compatibility has been very good -- the Excel equivalent of the scenario you describe wouldn't happen, because of the introduction of Future Record Types[1].
Word, Excel and Powerpoint were forwards and backwards compatible from 1997 to 2004. The newer versions emitted various backward compatible formatting (eg Word 2000 supported table-in-table, but emitted sufficient formatting for Word 97 to at least see one level of tables and consider the rest of the cells to be paragraphs)
I've had some particular cases where OpenXml docs created with Word 2016 looked terrible in Word 2010 because the layout was different.
Another comment here points out that word emitted tags for forward compatibility reasons. That's still true - I've had reason to parse OOXML directly and see those tags. I guess it sometimes isn't enough.
But I can see how the conflicting requirements to keep the upgrade treadmill rolling and never break any old apps have made certain versions of Windows into such unholy piles of kludges.