The concept of Managed hosting came up due to the fact that not everyone who has the skills to run a successful online business also has skills required to maintain and run his server. Running a server with almost zero downtime and troubleshooting it immediately when ever problem arises, becomes even more necessary if you have critical applications running on your site something like online store or online new service, etc. Thus it makes more sense to keep the server management with someone who is good at it.
Nowadays almost all hosting providers provide managed servers, which are completely taken care of by their appointed server administrator and other support staff. They take care of everything from routine day to day activities like backups to critical server kernel upgrades. Other tasks include taking care of server abuse from spammers, load balancing, preventing attacks from hackers, and installing various software to strengthen server security.
If you are serious about your online business then nothing will substitute managed hosting. With proper research inside the hosting industry and with keeping things like top-end server hardware, reliable software and efficient manpower resources in mind, you will be able to finally find your hosting company that you have been looking for.