Because it's competitive mode; their should be rewards for people who did well, not just hand-outs for everyone.
Like WoW has rewards (like mounts and titles) for the top whatever % per season.
Someone who wins 300 matches in the course of a season isn't necessarily good. Dedicated alright, but not good.
I think a gold medal should be a gold point and silver and bronze their own respective points.
edit: then again I don't think that'd be fair for support players. A system should be in place for rewarding individual players based on their individual success is what i'm trying to propose. Many a time I play a comp match and get mainly gold stars and not move up in rank if it's a loss.