Even though this marketing strategy ends up being profitable and it is a success for casinos to attract new gamblers that does not mean the search for better ways to decrease bonus abuse should stop.
Yes I am thinking sometimes that they are already knew it or they are also aware of it, they just let it slide so that many people will create account in their website and will give them larger traffic like the way they are planning, but they also know how much losses it will come back to them, so it means they already have the estimated amount of it, I think right now there's no one to blame with.
it is a win win solution or strategy from each site actually .
That would explain why I have seen people creating a discussion on the gambling or reputation board against a casino for allegedly decreasing their winnings or not allowing them to withdraw, etc . I have seen a couple of those where the apparent incident involved the use of a bonus, of course the casino had its back covered by their own Terms of service. The house always wins, if they allowed people to withdraw high earnings obtained solely through bonuses then they would not be in business much longer, specially small casinos with a tighter budget.