Which, to be fair, isn't technically dead. Apache OpenOffice, the rotting corpse of OpenOffice.org now maintained by Apache, released 4.1.16 just a few months ago.
What should have happened was that ten years ago Apache should have "retired" OpenOffice. That's Apache's terminology for projects which are abandoned. But instead it has limped on for all these years, sucking up valuable effort by users with Apache claiming that it'll be fine somehow.
Edit: Further, the ooxml format was heavily criticised ~20 years ago, back when it was introduced. This is old news.