Twitch has turned into a cesspool of gambling addicts and gambling pushers. Do you think it's a responsible content creation & moderation on a platform which is used by teens, kids, and young adults?
The platform could add a warning message on gambling lives and channels without completely banning it. There is no reason to ban gambling content just because there are kids accessing the website, otherwise youtube and every social medias would have to remove this content as well. Moreover, to educate people regards the dangers of gambling you can't completely remove gambling content from the internet. They must understand gambling exists, it's part of daily life, many people around them can be gamblers and their only option is to deal with this situation in a way they don't prejudice themselves.
If you pretend gambling doesn't exist by removing it from platforms like Twitch, people will have an illusion they are safe from its risks, while the reality is that they will not be able to deal with a gambling situation when they face it for real.