the answer I've seen over the years is usually
"the game is already dwindling, we like to give second chances because we can't afford to lose more players"
earf is most correct; we give new players the benefit of the doubt; repeat offenders get less and less doubt though; if they were new each time, it'd be less controlled i think...
Can't really block proxies because of how most of south east asia is basically on proxies since they've been running out of IPv4 addy's and are NAT'd; Australia too.
In other parts it's really easy to get new IP addy;s or IP addy's bounce around; or change & conflict with others....
well if they're gmail they don't even need to really; can do gmail with .'s in the name or with + after... and while we could filter that, that's a big PITA