I, like you, made a rapid transition from loving to hating school after leaving elementary school. I got very lucky that I intermittently had good school experiences later in my education as well — at a gifted kids summer camp in middle school, and at a gifted kids high school for my junior and senior years, where grades still mattered a bit too much with college admissions looming, but where at least curiosity and critical thinking were valued over memorization. But I also had terrible years, years where I begged my parents not to make me go to school, because it was full of tedious busywork and teachers who punished me for reading a book after finishing my work or for asking questions that would have taken us slightly off topic. And I have also been a tutor for years, and I have seen so many students crushed by the kind of high-pressure, grade-focused schooling you describe.
I actually avoided becoming a teacher for a long time in part because I was afraid of being forced to be part of a school like that. But I’m finally starting teaching this year, and I’m hoping to do better. I’m teaching middle school science and my biggest goal is to reward curiosity. Thank you for giving me hope for that to work.