The problem is that you cannot conduct a full study of the legality of the casino business - they are mostly registered in offshore companies and you can assess the legality of their activities only by the comments of their users (are there any problems or not). But even user reviews cannot be trusted as they can be fake.
Yes, if you make an account personally they can just let you withdraw, play and deposit normally but do selective scams. Only way to avoid this is by promoting well known and already reputed casinos so that you don't have to worry about the trustworthiness.
I don't see anything wrong on it, in fact Vloggers content creator and even this forum needs sponsors to keep up with he cost, it's not easy running a channel, creating a content, there should be a financial motivation behind it, nothing is free now, because you cannot keep up giving something for free, you need sponsors whether in kind or cash.
It is a very sensitive topic actually because one mistake from the streamer might mean that he loses his subscribers and even his followers on all social media handle within days of promoting a scam gambling site even if by chance and not by choice.
When you promote something directly and at times even indirectly, you have to take the responsibility and make sure that the people influenced by your content don't get to face any problems. Its similar to why some big actors or actress will never promote a new and untested product.