I'm a little bit confused by the RAID section of Production Notes
Here it says

Avoid RAID-0 with MongoDB deployments. While RAID-0 provides good write performance, it also provides limited availability and can lead to reduced performance on read operations, particularly when using Amazon’s EBS volumes.

To my understanding usually RAID-0 should work better than single disk, both read and write. Then why does it lead to reduced performance? Is there any specific reason?

Scope

Remove the clause from master -> 3.4