Halo 4 and Halo Reach both share a something and thats concern
a form of which is the MAPs and the avialable players in a splitscreen
as many of you should know playing a game on split screen can reduce frame rate causeing lag and disco. This accures due to the map being rendered multiple times over for each split screen
or
it can also come from a company built map that is to much for the game engine to endure
a good example from halo reach is beavers creek mossy tunnel even on a system link or solo you can get some frame rate lag as its over using the engine which was quite heavily effected by adding more players into the match
while some community map can require more frame rate than others they are either due to ingame building glitches such as Z-fighting or content such as glass and lights
while other methods such as an OVERLIMIT map which is a block class edited via computer to become another block class which breaks the amount limit. This can have an effect based on how much of these overlimit blocks are used.
Although the overlimit maps can add very Unique sense of satisfaction to both the builder and the players who enjoy this new experience. based on this overlimit factor it is safe to say that it must be played WITH NO SPLITSCREEN to provide assured frame rate that wont waver based on additional screens.
THE CONCLUSION FOR HALO 4 and Reach
for a community list only set the requirnments to block split screens in these particular playlists to provide higher quality maps and clean play above the norm for a 4-split average game. Though users can still join a group of freinds in the lobby they cant split screen.
Note: community list is only a single section of playlists