I think you're understating people's ability to listen to their own body, and using an ungenerous definition of 'feeling'.

Listening to your body is a skill that can be developed over time. Several years ago, I did not pay attention to, or was not aware of, any relation between what I ate, and how my body felt afterwards, what things looked like on the other end, etcetera. After starting to work out and taking my health seriously, I spent more time tracking things like 'how does food X agree with my stomach? How does it affect my energy levels when I have sugar in the morning?', and learned a lot. There are foods now I'm very hesitant to touch, that I would have eaten without a second thought several years ago, because I now know they affect me personally in undesirable ways.

This is not to say that one should eschew the scientific literature, or their doctor's advice. You should just take both into account.