It is certainly not my experience. I am a PhD student and since the very beginning my mentors (program directors, my PhD advisor, committee members) have been pretty clear about future prospects: "the opportunities in industry are such and such (compared to the opportunities for BS and MS)", "postdoc positions have those requirements", "the chances for getting a permanent research/teaching position is so and so".
While there are people who are dishonest with their students, it is borderline offensive to lump them up with all the rest. All the people I have worked with have been honest about job prospects and have worked hard to give me the best tools to work in those jobs.