Teaming isn't fun. the game is about strategy, teaming is just about randomly splitting and feeding no game play what so ever, its slow, repetitive and boring.
Before there was teaming agario was the most popular game, then people started to team and ruined the game. They thought they were special but they killed the game.
Every game has collusion and cheating, and its normally punished. the only people still playing this game are just losers who team all day long.
Years ago before teaming there was millions of people playing at any time and it was impossible to just get in a server.
Its simple make a room for teamers to waste time, make a game where teamers are perma ban. You just need a few moderators banning teamers and you will have millions of people playign 24/7. The ad revenue would be huge.