Actually people say gg because it is machined into them. They are conditioned to say it even when neither party played well and they played horribly they say it because the people they watch stream say it. It isn't good sportsmanship, just learned behavior. As far as toxicity I've spent countless hours telling RIOT how to fix their toxicity and it isn't by banning good players like myself. They actually love the toxic community because it creates more loyalty and fanaticism towards the game. So they will never fix it and most people like myself who get banned for what isn't even offensive and extremely minor compared to what people say to me (It would take me a few weeks to go through my recordings and find the countless times people have told me to kill myself on the game) they ban me simply because I stand out from the community for being logical intelligent and honest, something they hate in players (most modern companies do) and worst of all I receive more bans because I don't spend money on the game and RIOT ONLY cares about money.
But this all stems from a paper I wrote in school about how modern companies value the worthless masses because as a whole they have more relative disposable income than the few quality gamers that exist these days. That's how this problem of toxicity has become so massive in game communities. The industry wants players who are as disposable as their incomes so they can trade wins for loyalty and money thereby resulting in players who can't earn wins in anything suddenly winning at something and not knowing how to handle it like a quality person would. Then good players like myself come along and have to deal with these idiots where my other option is I can't play games anymore because all game communities have turned into this garbage (though none, save for WoW, are quite on the toxic level of League of Legends).
And league has admitted this and taken no steps to fix it aside from banning some good players. The other problem is simple you have one the absolute dumbest things anyone could ever do and to RIOT it is innovation. You NEVER give players authority over each other. The same way you wouldn't let your kids punish each other. Authoritative power needs to come from a neutral and unbiased source and not the same idiots that flock with the ones you are trying to educate and therefor ban you far more often than someone who is pro riot and pro league.