In the aftermath of the Snow Queen's spell, portals were opened up all over Storybrooke bringing in people from realms far and wide - across all universes (even the alternate ones). In a desperate attempt to protect the world at large from the influx of these newcomers, Regina sealed off Storybrooke permanently, making it impossible for anyone to leave the magical town.
I'm glad this place brought my daughter back. My son has his twin and Jenna has her alternate universe sister back, but I'd desperately like my husband returned to me. My children need their father and I need him.