Depends on what ya define "leaving" as. But yeah, no one's ever left.

[ Do others ever truly leave? The statues of countless unknowns leave him wondering what the truth is. ]

Well, Rinne-senpai "left", but Ohii-san and some other guy found his statue. Dunno what's going on there, though...

[ Are people returned to their homes? What do the statues signify? He knows vague details at best about Jin. Are they stuck here forever without an end in sight? He's almost sure they are, as the "wish" granting might be a complete and utter lie. ]