The reason I thought it would be helpful is that I am not a high feedback person. I seldom praise (need to work on that), I am not expressive, I've been told I 'play my cards close to the vest.' by someone who directly reported to me. That really got me thinking that maybe the circumstances where I am not getting what I want is because my staff really cannot figure out what I'm looking for in general. So I wrote up a 'read me', before I knew there was this trend.
I included self-deprecating statements about things like assigning a task to multiple people because I forgot it had already been assigned 'Don't take it personally, just let me know and I'll fix it.' And, if they need me to attend a meeting, make sure it's on my calendar, or, no chance I'll remember.
In the end, it's only going to be as helpful as it is 'correct' and clearly described. That depends on each manager's level of self-awareness, combined with their sense of self confidence. You'd hope managers would have both qualities, but if not, this can really be a red herring, or even be used as a dark pattern.