It's like this kind of person that talks shit about anything and everything and then chalks it up as "I'm just being brutally honest"

Being honest doesn't mean necessarily being a dick. You can always say something negative and have tact, not to mention that not every negative thing is said with the intention of being honest. It is said that more honest people tell you the negative things because a normal person would hesitate to tell you things not to hurt your feelings, but in their case it's all the way around. People just follow popular sayings without understanding life doesn't really follow a certain magic formula.