Just want to incite some discussion as I know I'm not the only one who's experienced this.
On multiple occasions I have been banned for negative attitude and/or unsportsmanlike conduct and the like, on this account to the point where it is permanently banned (though not from the forums). More recently, on my newer accounts, I have escaped such punishment by forcing myself not to type when I'm frustrated with my team. It's sad to me that I have to do this, because in reality those games I'd get reported and/or banned for would be pretty mild in terms of "negative attitude." I wasn't one to full blown cuss people out or threaten them or use hate speech or anything like that. Rather, I'd see my teammate facecheck a bush that he knows full well the enemy team is in (because we all just watched them walk in) with 100hp just so he can drop a ward (you know, to show us that the enemies we already know are in the bush are in fact in that bush, just in case there was any doubt), and I'd respond with something like "what the hell was that? you know they're in there... don't facecheck." Pretty reasonable thing to say to a teammate in my opinion. We need to be able to communicate with our team to tell them when they're doing something wrong or right or what have you. That's the whole point of having a chat feature. It doesn't need to get out of hand, but we shouldn't have to be afraid of telling our teammates they're playing poorly because of how they may overreact and report us, and we all know riot will side with them.
I know the majority of you who read my post and actually reply will be the aforementioned face-checker. The insecure, sensitive about my gameplay, and if you insult me I'm running straight down mid type of players. You'll attack my post and say any level of negativity is abusive and should be punishable, and I just want to say up front that I genuinely feel bad for you for being so insecure that you can't take any level of criticism in a video game. The vast majority of players who are on your team are trying to improve and trying to win, and communicating when others are way off base is important and quite helpful when done correctly and properly received. You shouldn't be so quick to the defensive and maybe think to yourself "yea that was pretty dumb, my bad" and move on. When you get offended and start striking back, you're just as bad and the whole situation escalates. But inevitably, the person who gets punished is the one who first said something, and not the person who retaliates.
I've highlighted some of my perceived issues with this rather unforgivable ban-system in the above paragraphs (specifically with respect to in-game chat), and I'm sure many of you can relate and fill in your own gaps as to some of the other details. I intentionally left out chat bans as in my experience these are often skipped and riot is quick to jump to permabans when summoners get frequent reports for negative attitude, even when those reports are mild as in the example described above.
What I want to highlight next is how the people who ACTUALLY ruin the game, i.e. the griefers, are rarely, if ever, punished. Even leavers just get a low-priority queue for a few games and then they're back in action, ready to ruin another ranked game. We even see high elo players complain about this discrepancy in the ban system as well as in recognition among the community (specifically, Super Metroid and Akaadian have tweeted about this very recently). There are players who will intentionally ban the champion you are hovering in champ select just to spite you, then pull out the "I can ban who I want to" card to try and rationalize it (happens to Metroid consistently with another high elo player that doesn't seem to like him very much). There are also people who hard int in game and get away with it by making sure their chat logs show how innocent they are. We have all had hard inters on our team and we all know how this looks compared to someone who has a bad game, so please don't come out with that nonsense to defend it. Then there's the people who pick something troll like teemo support with barrier teleport and aftershock after the jungler doesn't want to roll swap with them, and they get away with ruining the game too. The list can go on, but I'm hoping you get my point.
TAKE HOME MESSAGE:
With respect to chat logs, Riot should focus much more on punishing players who are exceptionally vulgar and obviously out of line rather than those who have a negative attitude because lets face it, not everyone is happy to lose, and you can easily mute someone that is bothering you in chat or via pings. Again, not excusing excessive verbal abuse, hate speech, or threatening statements, but these bans for negativity are excessive and rather unwarranted. People shouldn't have to fear a ban for telling their teammates they're playing poorly.
With respect to inters, we really need to bring the hammer down on these guys. These are the people who actually ruin games. People who complain and whine about the game in chat are kind of annoying, myself included, but you can mute us if it's tilting you and you can move on. Or you can consider what we have to say and think hm, maybe I shouldn't have facechecked that bush. I'll back off next time. But seriously, inters, leavers, and trolls are what ruin league of legends, and you can mute an inter/troll all you want but they're still going to ruin your game. But what ruins it even more is how much slack they get and how they never go punished, so they keep doing it. Shift the focus away from negativity and onto the people who are actually ruining the in game experience.