Hot motors suck. And since you don’t like burning piles of money, you want it as cool as possible. Keeping your fan over the middle of the can is a great (and arguably the best) way to cool your motor. And for the guys running the PR S1 V3, they didn’t have many options aside from the mad max style of shoe gooing a fan somewhere.
Ride Low waterfall mounts keep your fan as close to the motor as possible. Wide venting and fan angle allows the air to flow quickly and easily around the center of the can. And there’s plenty of clearance for motor tabs.
But that extra wide top piece allows for a bigger Ride Low wienerdog, so there’s that.