Of course you have to do everything yourself. Having a control panel that provides an interface for clients allows them to do self-administration. They can create email accounts, databases, and even add domains if they have a multiple domain account. But if you are small and don't mind doing it yourself, more power to you.
But a lot goes into creating a domain. You'll want to create a dozen or so DNS records for each domain, create the domain in Apache, setup website directories, create an FTP account, and setup email. The control panel automates all that for you.