This has always been the case, even back in the 1980s I worked with a guy who was banned from all the local betting shops as he was too good at winning. I used to go and put bets on for him. Now with online betting they have a database of banned clients. You have to provide credit card / bank details to start an account so you can't just make up names.
They like losers , start to win too often and you will have your account closed.