Of course there are people that can handle setting up and maintaining high volume mail servers with analytics, etc themselves, and have the time and resources to do it. If a capable sysadmin is outsourcing sysadmin duties... well that just doesn't make sense.
I could probably figure out how to rebuild a transmission, and I've even got the tools and an engine hoist to do it, but it's not exactly high on my list of things to do and I'd rather take it to my friend that does it for a living so I can focus on driving the car.