My experience is of being an analytical whiner throughout school, and then suddenly understanding the point when it was explained to me by a fellow analyst in university. I can't help wondering how much more I (and others) may have enjoyed English if someone had explained it sooner.

And I think you're completely missing the point -- the author's intention is not unknown, it is irrelevant, since the purpose of literature is not to explicitly convey a simple intention, it is to provoke a reaction in the reader; we first experience the art and second analyze which pieces of it are effective to make us feel how we feel. Intention of the author isn't interesting or meaningful. And to misunderstand that is to misunderstand art itself, which is why we see here people suggesting we "call a spade a spade" -- whatever that means.

And realistically your teacher probably knows a lot more about what the author intends than you do. There is a lot of historical context and other works that put the novel into context. But that's not even relevant; you're being taught to think and look for examples, it doesn't really matter if they were put there intentionally. When you develop your abilities and are good enough to think about literature past the high school level then you can start thinking for yourself, just like in every field, but when you're intellectually a child in the field, you need to listen and learn. Unfortunately most children are petulant and whine and decide since they don't understand it yet, it must be nonsense, and everyone who is an expert and has dedicated their life to it "didn't have any clue" and give up. Like you see here.