I think it's a mistake to say that the story isn't realistic therefore it can't happen and therefore the story is somehow "wrong". It's not a documentary. The strength of stories is that they can depict anything happening, however unlikely, in that set of circumstances. I'm sure that in a lot of situations people would react differently, but the story there is supposed to be a tragedy about how people will resort to "savage" methods to survive when they're removed from their context and the controlling minds that keep them operating in the manner society wants them to.

It's totally legitimate to believe that LotF is inaccurate to how things are in real life, and disagree with the point the book is making, while appreciating the book as a piece of literature which has some value nevertheless. It's not misunderstanding anything to hear the message and have that not work for you.