Because that's a completely unreasonable reaction to that comment. I probably wouldn't want to talk to that person after that any way. If a person is so sensitive that they're going to get offended at tame compliments I wouldn't want to stick around and constantly have to walk on eggshells every time I talk.
I understand a lot of the reasons people would get offended at things, but if you're getting offended over such benign things like getting called cute and people holding doors for you, then I'm probably not going to want to stick around. Being that sensitive is off putting.
Thank you!