With Linux, it's lot of beating around the bush. Overcomplicated config files, a lot of disabling and removing of things one don't need, having to deal with a messy and outdated firewall. With OpenBSD, I'd just have to change a few config file lines and lo and behold have one of the most secure and well-thought out servers the world has ever seen.
Also, with the existence of Puma, I don't see why anybody would want to use Passenger.
Also, with the existence of Puma, I don't see why anybody would want to use Passenger.