On a less confrontational note, I think options for moderation should lie with the individual streamers, not twitch as a platform. But then people call on the streamers to use those tools and at that point I think it should be noted that faulting them over "not doing enough" is silly. Moderating chat is not their raison d'être. And it's just chat. Maybe they are just indifferent or have other priorities than those who demand a different atmosphere.
At some point chat starts moving so fast that people can't have decent conversations anyway, at that point its value drops a lot where someone might simply not care.
And for the viewers twitch probably should make it easier to disable and hide chat completely. If they deem it not useful or even offensive it should take just a single click to remove it and use that space for the video instead.
I'm talking about website (sub-)communities. Different places have different standards, and frictions between communities can be seen as a turf conflict, an invasion.