I really can't think of how they would stop this.
Like genuinely.
The sites that manage these gambling rings aren't owned by Valve, and reporting the sites doesn't get them taken down by the domain providers.
In Steam the trades look the same as any regular trades between players, so if they wanted to stop the gambling trades it would require turning off all trades.
Do you know if anyone has come up with some way they could track and stop the gambling sites?
Religon was kind of a law enforcement system before governments could properly setup formal law enforcement.
It's a way to make communities self police.
These days, organized religion is a dangerous tool sitting around for random con men to pick up and weild.