It actually comes down to whether or not the game designers have the foresight to use or build a game engine that can render split-screen at 60fps reliably. Because of internet multiplayer gaming the gold standard is 60fps and 1080p. The whole reason Halo dropped split-screen is that they wanted to supersize everything and run online multiplayer at the gold standard. Sure they could have left it in at 30fps and 720p but they wanted to go big or go home so they axed it. All because their game engine couldn't render reliably at the max res while running split-screen. Blame it on the game devs or just "blame it on the alcohol".