Companies often update its rules and regulations in response to what its users are doing, and Twitch is no exception. The service is still growing. Some of Twitch's recent changes, however, are pretty humorous, including an explicit ban on self-destructive behavior, sexually explicit content, and dressing appropriately.
There are other changes, but here's the ones I'm alluding to:
This is an aside, but I love how Twitch wrote its updated ruleset for users. The reason people often skip over this junk is because it's crafted to cover someone's legal ass, rather than providing the user with a clear and concise explanation of what's being said. Legalese exists to protect companies, not users.