Two quick stories, one of which I've told many times in different forms:
Story one. When I was a young teenage writer, pulled back into both reading and writing by Star Trek fan fiction (do not laugh!), I sent a CompuServe note (no, it wasn't e-mail) to Vonda McIntyre, who was a giant among Pocket Book Star Trek authors at the time. I was already stewing over the question of whether I wanted to publish my writing, or just to write for myself. She told me then that true writers are story-tellers, and without an audience their story-telling will always feel incomplete. The impact of this statement has carried through to today. I think about this constantly when I'm writing, and it has defined much of my approach to the craft. That said, there's no way she remembers it and no reason she would have thought it would be that impactful when she said it.
Story two. Not too long ago a beta read a manuscript for a writer friend, whom I will leave anonymous to protect the innocent. I loved the book, gave it a big stamp of approval, made a few comments about how I thought the ending was a little abrupt and felt weird, but that it was still good. Lo and behold to my eternal embarrassment I realized, a couple weeks later, after my friend had submitted the book somewhere, that I had failed at reading a .PDF and missed the last two entire stinking chapters of the book. It didn't change my overall assessment of the book, but I sure felt stupid.
So here's the thing. You know never know. You never know when something you say or do will have a long-lasting impact on someone, either good or bad. Not every life-changing moment seems like one to all the participants. You also never know when you're going to be the person who did something totally clueless and stupid, so cut other people some slack when they do.
Giving someone feedback? Great time to remember the first story.
Getting feedback from someone else? Great time to remember the second.