Voice Chat?

I think that we can all agree that League of Legends is a very team oriented game in that team coordination plays a big role in the success of games. With this being said, I do not know why Riot hasn't implemented a voice chat system internally, like other team based games such as CS:GO. Being able to communicate with your teammates on a more efficient basis can make or break games to some extent, and in my opinion, really highlights the teamwork aspect of the game, which I think should be rewarded.

What do you think?