I assume it's just an easy way to keep people from that nagging FOMO that comes from going into a new holding pen.
But currently you can either be on the fedi and see all of blueSky AND the thousands of servers of the fedi.
OR you can be on blueSky and only see what blueSky wants you to see. And they pinky promise they will let you see everything... eventually it's just so... "technically complex" (it isn't)