As a developer, I find this an useful API to validate links of my CMS generated websites within my CI system. This way, using sync requests to my sites, I can easily await the results and fail the jenkins job or promote the deployment.
Not an use-case I have currently for myself, but I thought that wikis and other services that host content written by third-parties would be better if they checked broken-links and notified visitors and content creators.
Maybe my use-case is limiting my ability to think about someone paying for it.
