Microsoft doesn't have the greatest support for OpenOffice/LibreOffice odt either, although they try (https://support.office.com/en-us/article/Differences-between...).

The fact that 90% of the world is using Microsoft's format is certainly relevant for everyday use, but it's orthogonal to the question of whether an open source project can achieve feature parity with a closed source product.

File format compatibility is always hard and I'm not convinced MS does a better job reading odt than LibreOffice does with OOXML. But LibreOffice does have a reasonably comparable feature set, even if the UI is not as attractive.