I was always a good student of literature. I got an A in a 300-level university class in Spanish Renaissance poetry when I was in 11th grade. I went to a high prestige private university and I won writing prizes. I got accused of plagiarism my freshman year in college because, according to my teacher, my paper was of a higher quality than my experience and background permitted (I told him how I had done that, and he apologized).
Anyway, in my entire life I got two Bs in literature courses. One was my first college French lit course, and that was OK with me because at the time I had been taking French for only two years and had skipped the first two years of French, so there were massive gaps in my writing and speaking abilities. The other was a lecture course that I was taking for double credit, taught by my advisor, whose semi-official pet I was. The point of the double credit was to get some credit for taking his high-powered graduate seminar, which I was doing without being registered in it. I had to write two papers, one for the TA, and one that the professor graded. The professor gave me an A, the TA gave me a B.
Several things were going on: The professor liked me, the TA didn’t. I actually wrote a better paper for the professor than for the TA. But mostly the professor and the TA were different people with different ideas and tastes. I was much more in the professor’s thrall than the TA was, and he called me out for imitating the professor too much with less thought than was necessary to do it. At the time, the professor was among the biggest names in his field, and the TA was . . . a grad student. But the TA went on to a fabulous career, and spent many years as chair of the very department in which that course was taught. He was no second-rate dummy. And experience has taught me that there was a good deal more to his criticisms than I thought at the time.
I didn’t dream of whining to the professor about it, because I was fairly certain the professor would back him up, and I thought it would do more for my reputation to take the grade like a man than to try to get it overruled. In the course of my life, that B meant absolutely nothing (except that I got one more B than my wife did).
Some side comments:
– Some universities have grad students TA in their first year; others don’t. At least that’s what my kids’ friends have reported.
– My kid’s bff is a PhD candidate at an Ivy League university where she had been accepted as an undergraduate but declined to attend, choosing instead a public university to save about $70,000 in cost over four years. Her first class as a TA was for a course she had never taken, and she was only a few weeks ahead of the students. She was absolutely appalled at the quality of their work. She had to be counseled to go easy on them so she didn’t fail them all.
– The TA’s comment cited by the OP about using complicated words could be attributable to inexperience or not, but the comment about the kid not really having a point gives me pause. It’s usually very easy to tell if someone has a point. If it wasn’t easy to identify the student’s point from a cursory reading of the paper, then it was not a good paper, almost by definition.