Solo queue games are most often decided, not due to which team played the best or even which team had a really bad or really good player, but which team had the biggest flamer. Games shouldn't be decided 5 - 10 minutes in when a jungler ganks mid for a kill and now the mid laner is flaming their own jungler for the whole game because it was clearly their fault, or because an ADC died in lane and now the support is going to flame every decision that ADC makes for the entire game.
As soon as one person on a team starts flaming that team will probably lose because it distracts everyone on the team and brings everyone on the team down.
We can't voice chat with other players because of flaming, this should be extended to typed chat as well. At least in solo queue games where flaming is at its highest. In the vast majority of cases pings are more than sufficient to communicate with your team.