In a high-trust environment, candor is not perceived as hostile.
When you encourage people to interpret candor as hostility, you make everyone constantly afraid of offending others. It's hard to build trust and rapport with your coworkers in that environment.
I don't think calling someone an idiot, for example, is candor. I have plenty of trust and rapport with my coworkers, and I can't imagine them saying anything of the sort on this list to me. That's actually how we've built the trust we enjoy, by not engaging in the kind of language exhibited in TFA.
If you can casually tell someone they're acting like an idiot, it's (to me) a sign that you have a level of trust with that person and the ability to empathize/communicate with each other.
If someone comes to you in private and says, "Look man, you're really fucking up.", it hits different than "You might reconsider some of your recent behaviors."
It shows that you are emotionally invested enough to use empathic language, rather than make blasé/meek innuendos to avoid any chance of offending them. The point is "You need to hear this" and not "I want to avoid offending you", which feels more productive to me.
When you encourage people to interpret candor as hostility, you make everyone constantly afraid of offending others. It's hard to build trust and rapport with your coworkers in that environment.