I'm not sure where your idea about the "average experience in academia" comes from (I don't even know if such a thing exist, because the very word "experience" implies a subjectivity beyond the scope of surveys or other objective measures), but even given such an average more positive experiences do still exist in the head of the distribution. But concerning the point: even though my own experience in academia hasn't been exactly pleasant, my professors weren't the source of it (the "system" was), and always provided helpful advice and selfless acts of teaching, like the OP described.

Not really. Academia has it's share of assholes, but the probability distribution of encountering assholes is pretty similar outside of academia too.

Thing is, it can be very brutal if you are flaky. It has a very low tolerance for bullshit/lack of expertise and people will not hesitate a second to call others out on it - even in public.

Outside of bio/medical academia, I think the GP is very true to my experiences as well.