Being nice will never win you the games where your team has a 0-10 feeder.

But those games are unwinnable anyways.

Not typing except to make calls and occasionally say gj WILL win you games where the score is something like 8-10.

The reason is simple: in every elo, there are people who think they are better than they are and will get mad if they are not stomping.

If you prevent your team from falling apart due to this, but the enemy team doesn't, their rager will eventually make some really, really stupid mistake. It happens from bronze to diamond (I've seen it in plat alot). Deleting the enemy rager with a 5v1 gank late game and then snowballing it to a gg push is the #1 way to win even games. This can only work, however, if your team doesn't fall apart first due to your own rager. The very least you can do is to not be that rager who throws games.