It's also important to learn by failing (aka learn by doing). Like parenting, there are many things in organizational behavior that can't be learned until you experience it for yourself. Few of us can be told "don't do that" and will internalize it to the degree necessary, without experiencing personally what happens when you do "do that". These people graduating from top schools and going straight into FAANG are doing themselves a disservice of the worst kind, by missing out on important organizational learning experiences.
On that note, I recommend everyone either get fired from a job, or work for a company so bad you quit, at least once. I also recommend it at most once. :)
As for inverting a binary tree, with your experience you must realize that the very large majority of applicants are poseurs. You need to filter them with easy things like inverting a binary tree. Most companies need "doers" not "thinkers". Even at the highest levels of pseudo-management (staff and above IC), you really better be able to do this kind of easy stuff.