Sorry, I see no purpose for it.
1 FortWars, so undecided people keep the color but aren't "awarded" teamkills.
2 TDM's with people distracting the fight.
3 Alternative Gamestyles where teams are mere indicators of rank/position.4 Gamestyles where TDM is there is a big team and a small but freelance team.
... While the two last examples would be better off with some sort of relation system...
The third example is stupid because ranks as team wouldn't hinder slaugter of higher/lower ranks.