There is a breed of very narcissistic person in our culture that will always find a way to blame their inadequacies and their mistakes on those around them. In high school, if you are a teacher you have quite a lot of authority in the classroom and so even if your student is oriented in this way, they will just 'not like that teacher'. Helicopter and apologist parents are increasingly an issue but they aren't directly in the classroom.

In college however, students are grappling with their own burgeoning adulthood. They realize a TA is just another student with a few years on them. While the professor might be a bit out of reach, for a narcissistic person, it is easy to justify to themselves that they are actually above the TA in status/rank/morality/righteousness/sociability. Subsequently they can beat down the TA in the way that you mentioned. "All my problems are the result of your failures to address them". "I would have done better but the TA didn't like me." "Oh I hated that class the TA was a total nerd." "No one ever told me I had to do the assignments, I didn't realize I would be tested on this."

It doesn't help that people who choose to become a TA are often a 'helpful' kind of person, the exact kind of person that tends to be a little bit susceptible to these kinds of criticisms, even if they are untrue. The only way to move forward as a TA (and as a person) in this environment is to harden yourself in the ways that the article and many other commenters mention. That's my 2c anyhow.