A rat snake can eat 9-12 pounds worth of rodents in a year. Think about how many ticks are potentially on 9 lbs of rodents. Speaking of ticks, Some smaller species consume up to 4000 ticks in a single year. They have been proven to help control the grasshoper population which can be incredibly invasive.
It is well documented they play a role in controlling pests and rodents. We've had this conversation before, and you weren't convinced then, so I wouldn't expect you to be convinced now, but there are many credible sources published that have documented a snakes important role in nature.
It's just a matter of whether you want to educate yourself or not.