You're right- a degree doesn't guarantee a job, especially if the person is unwilling to consider doing something outside of the degree. One of the guys I knew in college had a 3.96 GPA after 4 years in an architectural engineering program and upon graduation, he got a job designing crane booms for Harnischpheger (P&H, now part of Komatsu), making over double the salary of an entry level architect. Related by curriculum and possibly by application, but someone studying architecture wouldn't normally look at this job as a likely possibility. Similarly, someone with a degree in applied Mathematics has an almost endless range of job possibilities- they just need to find something they want to do. OTOH, someone in a program where there's no demand is screwed.
AOC worked for Ted Kennedy's campaign and also for Bernie Sanders. Draw your own conclusions.
I went to see a friend at his upholstery shop and not long after I got there, my friends' son's high school Chemistry teacher arrived to pick up something he had repaired. The teacher had recently retired, mainly because of the changes at the school and among the changes was the order that they were no longer going to conduct the usual type of tests- they had to allow the students to express the answer in any way they saw fit. He just rolled his eyes when I mentioned Common Core Math and when I asked how they would expect to do anything in a college Math, Chemistry or Physics class (or in any kind of applied science field like engineering) and he paused before saying "You sound like you studied some kind of engineering".
A degree in basket weaving or some obscure area of study isn't going to result in a good job when there's no industry or demand for it in this country. When people expect something that's unrealistic, they need to know they'll be disappointed.
To get to your last paragraph- I think the answer is yes, both are at fault. My guidance councilor was useless and I have heard the same from many others. Some parents don't have life experiences that allow them to know what's out there, many do. The ones who don't need to ask for help in guiding their kids toward a future they can't conceive and may not fully expect or understand. Some people are too busy making a buck so they can support the family and it's hard to see where to go at the end of a long day/week/month/year/decade. Some don't bother or care.