This isn't specific to justifying a visa. This same method is sometimes used when the obvious choice non-cheap-labor hire has already been picked by the hiring manager, but they're required (for any of a variety of reasons outside the manager's control) to post the job.

When it's not used for visa indentured servant games, it's arguably a relatively decent way to to do things (don't put applicants through a charade of being considered, and you're already certain who you want to hire), but better would be to not post the job at all in that situation.