A person receiving positive feedback tends to feel better, be more socially comfortable and engaging, and to receive resources that help them on their journey.
This response and that assistance actually helps them become better. Better nutrition, more attentive and patient instruction. Etc. It's not just that things are done for them; it's that the feedback loops can improve their own performance.
A person receiving negative feedback tends to feel worse, to be socially uncomfortable and isolated, and the be denied helpful resources and assistance.
The negative feedback loop can result in that person withdrawing more and more. I've been there: Most people do not want to be where they are not welcome. It is one of the worst feelings.
Negative feedback loops tend to spill over into one's physical health, and that unhealthiness furthers the rejection.
It is not just the "big things." People with a popular appearance routinely get bigger servings, more engaged and attentive care. More respect.
It's pervasive. Pay attention. You'll see it all around you, every day, everywhere.
I've been burned a few times by "attractive" people who deliberately used this to their advantage. And I've been slowly figuring out, at an emotional, "feel it" level -- as opposed to intellectual -- why some people outright pre-emptively reject attractive people.
They've learned a life lesson: Interacting with those people too often places them on the losing side. Whether they are being deliberately used by those people, or just because of the comparative way they are treated by surrounding people.