8 players just ruins the flow of matches. You get third partied basically every fight (which against competent opponents means you don’t win that fight or live very long), you can’t play the OBJ (I don’t think I’ve seen a single OBJ match in FFA do anything than go to time) and even if you win fights 90% of the time you immediately get cleaned up by someone who saw the fight or just spawned nearby before you can even get shields back.
The number of people in an FFA match for Halo needs to be such that you can kill someone and reasonably expect that you’ll be able to recharge your shields or have them be almost charged by the time the next person shows up.