Many dedicated server hosts offer servers that are managed. They will work on your behalf to help keep the server running. Different hosts will offer different levels of management. Some will prefer to do almost all administration of the server and will work to ensure that the operating system and all applications are patched and up-to-date. Other hosts will update or patch the OS to current levels when asked. Some plans will restrict the number of hours of management available per month, while others are less limiting.
Whether to purchase a managed server, and if so, how much management is needed is entirely dependent on the technical ability of the consumer. If the buyer has a great deal of experience with managing dedicated servers, and has the time to do so, then server management isn't necessary. A customer with no systems administration experience will benefit greatly from having a server with management included. Ultimately, one must balance the added cost of management against the risk of server downtime.
It's also possible to purchase dedicated server management without the server. Some companies will manage your server for you, wherever it might be. It's possible that the bust deal might be to lease a dedicated server from a company that only provides the servers, and contract out with a management company to ensure that the servers are kept in good running condition