No one will disagree with that crewebiker, but that's not the point.
There are lots of people that don't want to pay website designers and just want to make a low cost site themselves using a CMS or site builder.
It's time consuming to set up and manage a Joomla site for them so you'd have to charge but it would be good to be able to offer your clients a more simple, low cost branded system they can just use themselves. Generally web designers don't want clients with very low budgets so why not offer them a self build system where you still make some money but do no work, you also keep them talking to you for when they want additional services or an upgrade.