I agree with you but you shouldn't forget that most viewers of this kind of videos are very young and one part of them is not adult. Then there is a need to find a way to prevent them from being abused by those scammy/fake demos.
And this is the problem, if the audience of those kind of channels were people that knew that this kind of promotion is not real then there will not be such a huge issue, but many of those watching that type of advertising are people that do not have the experience necessary to know that what they are seeing is not real, and since they trust the streamer they try their luck in a casino due to that publicity thinking winning is as easy as what they saw in the video only to realize too late this is not the case.
Yes but for the children the problem is more complex than that because even if the child/teenager is aware that the streamer is not gambling with real money he will lust after gambling because he won't be aware as an adult of what money worth actually and how people are making money on other people. He will be naive about his actual chances to win in the long run and how much he is likely to win or to lose.