A number of other new ABC series debuted before the start of their second season, according to Screenrant, causing some fans to wonder why Agents of S.H.I.E.L.D. did not. They and Variety both speculate that it could be about DVD and Blu-ray sales, which are often hurt by the presence of a series on streaming video on demand services like Netflix.
It's equally likely that you can chalk it up to "It's Marvel." In many ways, Agents of S.H.I.E.L.D. is treated differently than other shows, not least of all to protect its secrecy.
Marvel will of course be debuting Daredevil on Netflix as an original series in 2015, followed by Jessica Jones, Iron Fist and Luke Cage. Those will culminate in a Defenders series that will group the four a la The Avengers.
Marvel's Agents of S.H.I.E.L.D. airs Tuesday nights at 9 p..m. ET/PT on ABC.