If I merely change the mac address in the device connected to my cable modem, I get a new IP, every time. Combined with the fact that the game is free, so you can easily make new steam accounts.
summary: guy found that the IP and steam ids can be rotated with low cost, so he used the in-game web browser to set a persistent cookie (on that installation of the game), so once cheaters get banned, rotate their IP/steam id, they'll be banned until they clear the app's data.
Yes, I agree! for techies on here, they'll know that as well.
The target here is script kiddies —whose tech knowledge is limited to downloading a program from github and following easily laid out instructions — which it's pretty effective protection against.