Conflation of politeness, niceness, and kindness:
All three are good ideals to strive for, but all three are also contextual. They also conflict with each other. The best constructive criticism is polite and kind but not nice. Social white lies are polite and nice but not kind. Certain speech patterns are kind and nice but not very polite.
Assholery is like a scalpel. It has its uses, but you should be as precise as possible and then put it away.
Source: https://lobste.rs/s/wcqcus/how_be_nice_programmer#c_fcpwuf