After the inception of the MCU, countless studios have attempted to create their own cinematic universe, and adopt serialized storytelling into their business model. Warner Bros. brought the DCEU to life starting with Man of Steel and Batman v Superman, although there were some missteps along the way. Todd Phillips recently explained his choice to separate Joker from the rest of the franchise, saying:
Article source: https://www.cinemablend.com/news/2479584/todd-phillips-explains-why-joker-isnt-connected-to-the-dceu