Yeah, I almost want to make it now to drive the point home to those folks. (Edit: emphasis on almost)
who cares if they can see my public posts
Misses the whole point, Open Lemmy Stats probably wouldn’t display your posts (lemmy itself does that), it would display all of the analytical inferences to be made from those posts, votes and other activity, revealing more about you than you intended or even were aware of. Which isn’t readily public in the way some folks are making it out to be, it takes some work to get that data and you need sysadmin/database/programming skills to make it manageable and useful. OpenLemmyStats will let anyone of any skill level query your data that otherwise would require you to be, at a minimum, an instance admin to get to.