I once had a boss who took pride in being blunt, as I have often done. But my boss’s bluntness sent me the message “you are beneath me so far that I don’t owe you common courtesy, and if I hold you in such contempt, I also don’t have any expectation you’re capable of doing your job,” which often undermined his message, such as “cross stage right and say your line.”
Bluntness often obscures rather than clarifies the intended message. Tactlessness is about the speaker, not about the listener (think about the really mean theater reviews you’ve read, for example.) Now a days, I aim at being direct but not overly blunt, or tactless. Alas, I often miss the mark, because I’m still too hung up on making you thinking I’m smart, rather than communicating with you.
And so the wheel turns.