Because for better or worse. Tanky central is the flagship development server for the Lemmy software. And if as an admin you want your issues or concerns to at least pretend to be heard. You must give the campist undue deference.
Your server at least also has a piefed interface. Don't know if world ever will. Though I definitely would encourage it.
Because the major instances are the ones most likely to need support. That and many of them good or bad try to look neutral.