Because it's an obvious marketing gimmick. They're doubling down on the hardcore reader and pushing fan service so hard it's almost unreadable. Because everything is in the same universe, they can push aside and bring back characters and storylines like it's the fucking stock market. Rather than focus on creativity and good art, they have this self-fellating obsession with reworking the same dried out piece of clay until it turns into sand, then they boil the sand into glass and break it. It's more like looney tunes than anything, just character-driven Mad Libs, professional fanfiction to generate hype for figurines and ticket sales.