It does not make senses, if casino always letting newcomers to win then all casino will be bankrupt in case all gamblers create new accounts every time they want to gamble.
I'm sure people do it, the result wont change as gambling is still gambling where luck is the main factor that lets you to win not your account. It was just coincidence if you win with new account.
It does makes sense. Think of it as a ploy of the owners from casinos or gambling sites so these new gambler will be able to enjoy his first gambling session and will be going back for more in the next days or weeks until he is addicted to it.
I am not a sure about this but it do makes sense if you think it like that. In the past, I tried doing some sample bets on old gambling sites. You will notice that you are winning great values with it, but if you tried gambling for sure, depositing your own money you will be realizing that that is the thing you will be regretting for all of your life.