Take happymod for example. The advantage it gave to players was really trivial at best (so you can find the flag carrier and see through walls in Trbes, whoop-dee-doo), but there are people who literally make it their life's objective to accuse other people of cheating. For an example of this effect, just look at some of the threads where people are accused of cheating; they are so long and ridiculous. Even if every player on a team uses happymod, it would have little effect on the outcome of the vast majority of ladder games in Tribes.