Why don’t people like straightforward/blunt people?

I mean even when someone uses tact, they still get disliked.
I’m a honest person and when someone ask for my job opinion or the truth, that’s what they’re going to get and I’m not sorry for being honest. I do use tact though.
My best friend asked me why a lot of people don’t like her new “friend”. Yea I quoted friend because that girl didn’t respect her. So I didn’t sugarcoat it so I told her the blunt truth kindly, but she didn’t take it well. She got upset that I told her but I’m her best friend, I gotta tell her the truth. She didn’t speak to me for a while but later realized I was right about that girl that used me and took advantage of her and quite frankly, didn’t even she didn’t even like her that much. I can tell she didn’t like my best friend and was jealous of her success and everything. I’ve been trying to tell her for a while and also when her boyfriend was no good for her and deserved a real man.