A problem for Microsoft? or one by Microsoft? Yes, sure it's caused by Microsoft, but it has to be fixed on the LibreOffice side, since I am sure Microsoft won't do anything about it.
Not until they have competition able to break their lock-in, till then the craziness of their format acts as a barrier to entry. So again, it's a problem created by Microsoft, but it's a problem for their users and competitors. And that's why it's not going to be fixed.
It's not nearly as big a problem for Microsoft. First of all, the compatibility problems are much bigger between LibreOffice and MS Office than between different versions of MS Office. Secondly, if you tell your colleague, "Oh, the margins are screwed up because I upgraded to MS Office 2051", they'll just shrug it off. If you tell them, "Oh, I'm using this new software called LibreOffice because blah blah blah", they'll probably yell at you for being a moron and wasting their time.
If my colleagues ever said I'm a moron and that I'm waisting their time for using LibreOffice ... I would tell them to either buy a Windows+Office license for me, or otherwise go fuck themselves.
> Yes, sure it's caused by Microsoft, but it has to be fixed on the LibreOffice side
You can't really fix something when the spec is incomplete, ambiguous, and refers to non-disclosed information, all the while multiple official implementations exist that contradict both themselves and the spec about the behavior to have.
Now what about Microsoft implementing ODT correctly?