The whole purpose of the Range Rover Sport's positioning was to grab some of the sport luxury SUV class that includes the Cayenne. That has been the sole reason for making variants like the SVR with seats like this:Brands self-select their clients through their positioning. Are there people who don't care about or get brand positioning and shop everything in a price range or size class? Of course, but that's not what we are talking about.
They could've just made a smaller Range Rover, but they didn't as they knew there was some addressable market outside their typical circle.