so you have the option to show/hide nametags in teams. but when you set it to always. invisble players have still visible nametags. even to the onther team. breaking their invisbilty. and on some pvp maps.
its just way to big to just seek for enemys. like when your only playing with 2 friends on a huge pvp map with invisiblty potions.

or you have a survival server with teams

invisbility potions are then just useless