Using that Dunkey video to try to support your argument is pretty much admitting defeat since it's a known fact that he lied in it, which Lyte proved back when he still worked at Riot. To quote Lyte:
What do you think about vgdunkey's ban?
It's really unfortunate. Many Rioters love Dunkey's content, and I've unloaded my share of "Not even close babyyyyy" jokes around the office; however, we really can't show favoritism to someone just because they are a pro or a known content creator. This isn't really a debate about whether trashtalking is OK or not OK in games; we've talked a lot in the past about how we're OK with players bantering with their friends but you should be careful when interacting with strangers who may not understand your intentions--especially if you're using hate speech or slurs. We have a zero tolerance policy against hate speech, racism, homophobia, and sexism and that policy stands whether you're a random player, a pro player, or a Youtube celebrity.
This also really wasn't a case about intentional feeders and whether it's OK to be toxic towards other toxic players--there wasn't even a Malphite in the game that got him banned and either way, retaliation just isn't OK because it makes the experience worse for everyone else in the game.
We know that players have been asking us to be more aggressive against intentional feeders for awhile, and it has taken us a bit longer than we'd like. We do consider gameplay toxicity just as serious as verbal toxicity, and are launching a new Intentional Feeder Detection system in 5.18 that can ban feeders within 15 minutes of matches. We're starting with conservative settings to make sure the system would not ban players for having the rare bad game, even if it was a 0-10 type of bad game but this is a great first step to aggressively tackling intentional feeders.
At the end of the day, this incident sucks for everyone. We respect that Dunkey hasn't posted his Reform Card, and I'm not going to post it either. Best wishes to him in the future.
That aside just because a select few can't use chat without flaming or harassing others doesn't mean the feature itself is bad. Plenty of people are able to use it just fine with no issues. I've personally had many experiences with all chat where the enemy team didn't flame us and vice versa, such as the couple games of ARAM where I went deathless as Janna (which coincidentally ended in a win for my teams). If a person is gonna use chat to flame or harass others then they have no right to complain if they get punished for it.