In no other sport is your practice environment so dependant on playing with 4 new random players of varying skill level (lower than you) every game which can be infuriating . Another unique thing about eSports is that players get a ton of practice exposure with the community through streams and soloqueue. See a correlation?
Since passionate players tend to show a lot of emotion ingame both positive and negative, they have to adapt to this. Some players like Forgiven just dont bend this way and have a hard time. How players deal with it vary from person to person, depending on how emotionally stable/mature they are. Keep in mind most players are very young and have never been in such a demanding situation before. For many, emotions are hard to keep in check.
Forgiven is a really nice and passionate guy IRL. How Riot punishes their players is completely up to them, and we the players have to adapt accordingly or face judgement. Riot is our boss afterall, and if we want to keep our jobs we have to act like it.