Humans are rational creatures. They try to rationalize everything (which is one reason why I have only found ONE critiquer that school is beyond horrible: Piotr Wozniak!). Thus they get very mad when unfair things happen, which is a basic law of darwinism, but for school, the alternative theory is that combined with the human brain's natural defense mechanisms to forget what is not recent or pleasurable, rationalization becomes even more likely.
Otherwise the thought that they are overthinking when they are overthinking actually leads to less critical thinking