An education, regardless of field, should serve the purpose of building your skill set. While this runs through many strains of higher education, art school in particular heightens this skill-driven education rather than a degree-driven one. A degree from an art school, regardless of its prestige, isn’t terribly relevant (outside of a select few majors). It’s what you learn there — or rather what you CAN learn there — that are some of the most priceless and wholly tangible skills that a school can give you. It’s stripped of much of the monotony and hoop-jumping of traditional schools in that what you learn is evident through the quality of what you make rather than a series of memorized facts and test-taking. Those still exist, but in microscopic numbers and only in select classes.
Your friend is like many kids who go to art school because they think it’s the easier, “more fun” route. I complained about tough professors (like any student in the history of ever) who took away my “fun”. The difference is that the harder the teacher I had, the more it pushed me, and though I received letter grades to mark my progress as well, you also get your drawings, paintings, sculptures, designs, animations, etc. as tangible products of what you’re ACTUALLY learning from the people teaching you. No professor can be like: “Remember how you picked C when the correct answer was D on question 17-E of test 3? Here is what you can learn from that” But at art school, your growing portfolio becomes a timeline of progress and reference for teachers to meticulously critique to help you improve.
I don’t think that there’s much validity in those claims that teachers are too harsh/mean, but I won’t assume that they didn’t work hard enough. Laziness and excuses are certainly the easy things to point at (and could be all there is to it), but as crazy as it sounds, the emotions of it all are hard to swallow — and some people might be hard workers who just feel too much or take it too personally to cope. For me, I think that people believe that teachers at art schools are so much harder than they actually are because they’re dissecting something you’ve created instead of marking you down on a series of missed multiple choice questions. That vulnerability makes it more personal and it “hurts” more when you falter, but man… when you succeed… it can be like getting a fist-bump from the ghost of Leonardo da Vinci while he gives you vague but heartfelt words of encouragement from Star Fox 64.
"Never give up. Trust your instincts."