If someone's doing well, be nice. Otherwise, say nothing. It's not that hard.

Last norms game I fed really badly, and 3 out of my 4 allies decided to bad mouth me for the rest of the game (they're the typical trolls who aren't afraid of threatening people and getting reported). They made every single death so much worse even though they ended up feeding later in game just as much, but even then I'd still congratulate the team for getting kills and taking objectives.

After game I felt terrible, how could people actually enjoy doing this to others (they actually explained that they were being like that to make themselves feel less bad). Afterwards I remembered two games ago when I was pretty fed and everyone was friendly, and honestly, without their small compliments my day would've felt so much worse.

So if someone's doing well, please compliment them, even if it's a small gj or 'nice lol', it may mean a lot more than you think. If they're doing terrible, encourage them, or simply stay silent. Don't make it any harder for everyone.

EDIT: found out the 3 guys were in a premade, 1 was unranked, another had like a 20% win rate in bronze and the last one was level 26...