(NEW META)
That's mainly because you're playing in low rated matches since you're new to the game and you're put in matches with other new ( possibly new to moba's ) or plain bad players that don't understand the game and, for one reason or another, keep losing. I'm not saying that once you're out of there, matches will be devoid of trolls, whiners, flamers, russians ( or BR's in US I think? ) but something like 1 out of 5 matches has a chance of actually being somewhat balanced and fun.
That site currently puts me at 1566, top 0.05%, even if last week I clearly threw at least a couple of games. I like how false this notification can be "Playing selfish will decrease it." since I'm the living embodiment of selfishness in this game.