I hardly ever encounter people attempting to boost each other's stats. If I see a large team all giving a win to one specific player in a game, I'll go and check said player's game history to make sure they aren't breaking the rules and 9 times out of 10 I'll find nothing wrong, they may have just been recording, streaming, or just having fun with friends and that's what this game is about in the first place.
However, we all do have that competitive side in us, which is why Solo SG is coming very soon to satisfy the needs of those who want to play without encountering teams.
To be honest, I can't wait for the Solo servers to come out, so I can play on the regular servers without all of these people harassing me for playing with a close IRL friend. No joke, I'll join a server with said friend, we'll be a team of 2. There will be at least one person, if not two, who will openly harass him and I for teaming, calling us noobs, saying we suck, we can't win without teaming, etc. And it really, really gets annoying because while I myself am surprisingly competitive, I can control this side and understand that there is more to this game than just trying as hard as you can to win.