... which were exactly the thoughts and reasons behind Apache accepting OO in the 1st place. For various reasons this obviously never happened. But it WAS the idea from the start.
What actually happened? For some reason, development on AOO stalled. What little work still happens on it, is almost always replicating work LO already did two, three, sometimes five years ago. See it for yourself at https://cgit.freedesktop.org/libreoffice/core/log/?h=aoo/tru... : pick a commit, and look for the "Notes" field. For instance, picking "Port main/fileaccess to gbuild" I see the note "prefer: 1f9bc2b2aa8168f9c164044058b117d2a17d83ad"; that git hash is for a LO commit from 2011 (https://cgit.freedesktop.org/libreoffice/core/commit/?h=aoo/...).
In the meantime, LO did a lot of cleanup work. Finishing the build system move to gbuild, cleaning warnings across all the code base, removing plenty of obsolete or unused code, running several static checkers, and more. As I noted at https://lwn.net/Articles/699108/, the recent AOO CVE was probably found and fixed on LO two years ago, as a result of running a fuzzer together with valgrind. If you wanted to pick an "upstream project" to base an office suite on today, it makes more sense to pick LO instead of AOO.
https://news.ycombinator.com/item?id=12414681
So you did get your wish, but it's not the LO people at fault.