Web design firms, web developers or a systems integrators are companies or people who usually double as a web host reseller. Apart from the services they render, the hosting becomes an added value for their company. Without requiring too much technical knowhow, web host reselling is one of the better ways to start a web hosting company.
The reseller can basically focus on business as the technical stuff such as the maintenance of the infrastructure is taken care of by the datacenter operator while configurations, upgrades and server security are the responsibility of the dedicated server owner. Resellers are even able to look less like a reseller since they are capable of customizing control panels and name servers.