Seriously these streamers don't care about their audience.
See YouTubers like RiceGum, JapePual.
And recently I've started watching a streamer from the league community and he's promoting a well known gambling casino to their audience knowing full well the majority of the audience is under 18. But that solves after they put 18+ in the video but does that work for people who wants to break rules whenever they can?
They really don't. Although I'm not following that much those streamers and content creators that focus more on gambling I see them once in a while, people should be careful with their strategy of convincing their audiences. I think there's a psychology impact why these advertisers are also choosing some line of audience like an age bracket that they're targeting through these streamers because they're likely to be the ones that are very much active.
Those streamers may not realize it but what they are doing is dangerous, when we see an ad on television we have no possibility to interact with the person promoting the product and this is obviously even more true if we are taking about someone famous, but those people not only have big influence over their viewers, by interacting with them they can more easily convince them about buying or using the products they are promoting, which makes this a very effective way to market something and it makes even more insidious any kind of fake advertising.
That's the purpose of advertising, to tell white lies about it so people would use it (either a product or a service) by paying influencers to promote it even though the influencers doesn't even really use their products. They only do such marketing because in that way, they could easily persuade people to appreciate their products and make a huge sale.
In YouTube, there's a notification or warning if a video is not suitable for young people like below the legal age. I think it's the parent's responsibility to always watch their children's activities online.