We can't do anything about these kind of players, they have the right to express their thought but obviously readers are not that naive to just believe anything without confirming the case. Anyone can write a review which they think is appropriate but reader especially the one using the same casino can verify it according to their own experience just like how you react on that post.
I understand that reader can verify those claims. But I don't think potential new players will check every review in detail. They will see the overall ratings and judge the casino based on overall ratings. It will serve as a red flag if it's low compared to others. On the other side, existing players who have played at Duelbits before might be interested in reading in detail. For sure, they know where they are playing and what this casino is offering to them. The worst scenario is a negative rating just because someone is unsatisfied with the bonus.
As a player I would not just jump easily when I see newly created casino with good promotions that gives a player a bit of an edge. I would rather stay on the proven casino and had established its reputation over the years. Besides if one is aiming for VIP rank, it would be a waste to play on newly created casinos since we have to start for the ranking all over again.
I would do the same. But, I have a habit of checking new casinos, how it's going and what they offer. I may try out new casinos with some decent deposits. That doesn't mean I will move there from where I always like to play. Since I like In-house games and love to participate in content, I might try it if new casinos offer something like that. However, reducing the bonus or cutting essential features is a disadvantage. Even Established casinos will lose a portion of users if they do it.