We have many different systems in place to prevent scammers from making new accounts. However if you have a good level of technical understanding, you will be able to bypass these systems. To be clear, this is not one system that checks IPs, we have a dozen different systems and we look at many different data points.
Some systems only trigger alerts, but no action, in these cases staff needs to review the alert to decide if someone should be banned. In these cases, there can be a delay from when the alert was triggered to when the scammer is re-banned. This can give the appearance they were able to make a new account and nothing happened.
It is not possible for any website to block anyone permanently. Not Facebook, not Google or anyone else. It's simply impossible to block someone permanently. Hardware bans are by far the most effective, however it's not possible for a website to use hardware IDs. In order to access hardware information on someone's computer or phone, an .exe program must be installed. Obviously this is not something a website can do, because visitors are not going to install something just to visit our website. Some games use hardware IDs to ban cheaters, however in those cases the player has to install the game so the hardware ID can be easily recorded.
If you know someone who has created a new account that was previously banned, please click the "Report" button and we'll take a look.