Exchanges and casinos block ips from the United States but everyone just uses a VPN, why even block their ips in the first place when you know they are going to do it anyways. I'm guessing they do it so they have some type of deniability?
Because of laws and regulations where if they do tend to accept users on such country which do restrict gambling then they would really be on a big mess.
So IP ban is the solution on restricting those users but as said this is pointless due to VPN but well once you've been caught on violating countries laws then you would be fucked up.