It doesn’t really matter if the specs says one thing and the “indie MS dev” does another. Since MS Office was the first and most common and adopted solution it kinda sets what is the standard. When LibreOffice refuses to copy the way Word displays a simple bullet list because Word isn’t following the spec then the problem isn’t with Word, the problem is in Writer.
This is like those bugs that people rely on. Even if you can argue there’s a few lines of code that aren’t doing what was technically correct as soon as you’ve people depending on that “wrong” behavior for some task it suddenly became a feature and the right way to do things.