Do philosophy departments encourage an overly-optimistic view of the job market? Yes, they absolutely do. Think about the way departments often talk about their placement records. An old Leiter post has an example of Columbia claiming that they'd "recently" placed their students in jobs at Chicago and Harvard. What does "recently" mean here? In means these guys got their jobs over a decade earlier.
But this is just par for the course. My own department's website has a list of big placement successes that goes back to a time when Kurt Cobain was just a skinny high-school kid trying to find decent punk rock records in Aberdeen, WA. Of course, the website doesn't tell you my department's got to reach back to the pre-grunge era to put together a list of placement successes. And it doesn't tell you it's not listing the people who never got tenure-track jobs at all--even though they make up nearly half of each class. No, the website just makes it look like grads from my program get all these awesome jobs at super-awesome schools.
A grad student looking for a clear-eyed sense of the job market has to see her way through that bullshit. And that's not always easy.