"It's as if you offered Windows 3.11 support", a friend of mine said. Well, yes and no. The newest version of Joomla CMS is 1.7, and 1.0 has been unsupported since 2008. However, there are many websites made on 1.0 that will not upgrade to 1.7 simply because it's too expensive. If someone ordered a page made with Joomla and a slightly modified off-the-shelf template, it's not because he has a large budget. Now, try explaining that person that he needs to spend the money twice or there will be countless break-ins into his page.
That's why we decided to offer a service to help these people out. Most of these websites are now in maintenance mode, only content is being added/edited and no major redesigns are taking place. We just lock all the files and, optionally, parts of the database, and that's the secret sauce. It makes Joomla 1.0 hosting pretty secure.