Now that you gave us the "Limited - Google can not see it feature" you can make everybody happy.
(1) Allow "Google visible" posts to only post in the 300 topics you have created
(2) Allow "Google invisible" posts to post to any group - cause it no longer makes a difference for those.
(3) Allow us to once again create groups (prefixed with "I"), since the only things we can post there, would be Google invisible posts.
The benefits?
* Downvoting would only hit google visible posts, since viewers of Limited posts are not likely to be downvoting anything.
* You would not have to invest effort in merging the million "Limited only" groups - cause there would no longer be a benefit in doing so.
* People could keep their beloved groups, for identity purposes - without causing harm.
* People would be able to add groups - knowing they could only post "Limited" posts there - everybody could live with that.
And all would be quite happy ... harmony would be restored
* * * * * * * *
Personally, I could then ...
(1) Create groups like "I love ice cold beer or I love DQ Blizzards" ... meaningful to me
(2) Write stories tailored to the audiences, narrow as they may be.
(3) And not concern myself about downvoting
The reasons for eliminating downvoting are hugely reduced ... the need to further merge groups eliminated and you could restore the individualism to add groups.