I dont think it is fair for players who do extremely well in the first 5 mins of a game to get no experience and no IP for a quick win. Just because 1 or 2 players quit early game, does not mean that the players who stay should get nothing.
Example: 3v3 normal matched - me and my friends kill all 3 players in the first 2 mins. 1 player quits for some reason, maybe a rage quit, i dont know. 2 players keep playing for another 2 mins, but still die to the 3 players, another player quits. the 3 player team, kills the nexus 7 mins into the match. this is the first win of the day for the team, but the team gets no exp or ip for the win and the first win of the day bonus has been wasted by doubling a win where they received no IP or exp. I think something should be done to handle this slightly annoying issue.
PS: I dont think its fair that a team gets nothing if they win a match to quickly, especially if the other team has no leavers.