343 Industries, the developer of Halo 5: Guardians has confirmed/explained why the game does not have a split-screen multiplayer mode.
“The decision to remove split-screen support from Halo 5: Guardians was one of the most difficult ones we’ve ever had to make as a studio.
We know that for many of our fans, Halo has meant playing together with friends in the same room. We all have great memories of past Halo split-screen multiplayer matches.
To move Halo’s gameplay forward and deliver a true next-gen experience, tough choices had to be made. Our decision was driven by a desire for scale, fidelity and focus to ensure that we would deliver the best quality experience possible.â€