See, this is the piece that makes me assess this as an abusive thing to do:
The key, I find, is to be extremely direct and brutal in one on ones.
I have two special needs sons. I'm a former military wife. I tend to err on the side of being super, duper blunt and, no, my kids don't get "hints." But that doesn't mean I have to be ugly about it most of the time either.
Real life example:
When they were little, I would say "The trash is overflowing and needs to go out." My oldest would look over his shoulder, see that this statement was factually true, acknowledge the veracity of it and continue playing his video game. The fact that my statement was intended to get him to take the trash out did not quite click.
There is nothing whatsoever abusive about changing that statement to "Son, you need to stop what you are doing right now and take the trash out." That's just clear communication.
I am well aware that some people think saying something like that is somehow emotionally abusive or some nonsense. I have spent plenty of time on parenting lists where people were horrified that I would tell my sons something directly instead of dropping hints or some nonsense.
I'm quite fond of the movie quote "I'm too truthful to be good." I'm also very fond of a rubric I learned long ago that "Those who believe in telling the brutal truth value brutality more than truth."
I can be very, very, very blunt. I try to always be kind, to the best of my ability. I see no contradiction between the two.
Learning to tailor your communication style to the needs of individuals on your team is just good management and doesn't require any meanness whatsoever. In fact, it's a kindness.