Forget split-screen, a lot of people have two monitors these days. Steam hardware survey has “Multi-Monitor Desktop Resolution” as “other” for 50% of their users, which I’m guessing means about 50% of people have multiple screens. Think about it, game devs.
The issue isn’t screen real estate, but processing power
When you do split screen, you’re basically having to render two games at once (a bunch of stuff can be “shared” like physics and such, but you still have to render two PoVs at the very least). This is helped slightly in split screen by the fact that you’re rendering a much smaller PoV for each player, with multi-monitor split screen, you lose that edge.
Basically it could totally be done, but only on pretty decent hardware and/or a really efficient game
It’s almost like the pursuit of realistic graphics hamstrings games by making actual fun, useful features like couch co-op impractical
It’s also that you’re rarely going to want to spend that much development time on a feature that only works on one platform out of 2-4.
