People moderate their own twitch chats with volunteer mods or using bot admins, everything they do is at their own discretion.
Of course gaming companies haven't come out and said it because its a no brainer, they aren't distinguishing from types of harassment like you are right now - you're seemingly just focusing on female harassment here and how to stop that. Harassment happens across the board and there are already punishments out there for that.
Again, how are you expecting this to be enforced and upheld? If there was a way to hold everyone accountable it would be done.
You're living in an Utopia that just doesn't exist, it is an idealistic fantasy at best.