Twisted Treeline Blues

Why is it that a fair % of the matches that I encounter here have computer generated bots? I just finished a game that was 3 real players against myself and 2 bots. Does matchmaking have to be so cruel? Riot, is there a reason why I am paired up with bots and not real players? Then I just went afk to let the game finish and got a leaver buster warning, of which I have never got before. Game play should be at the forefront of your design and development choices, why is this so lop-sided?