Tim, thanks for taking this up. At the end of the day, I believe it comes down to how you define “management”. In my world view, if a manager does not engage in the “hard work to learn about the people they lead” (as you put it), then he or she is simply a bad manager.
My biggest hero on management is Peter Drucker, and interestingly he did not write about leadership — simply about management. He had an extremely people-centric view of management, as evidenced in this quote: “You cannot hire a pair of hands, it’s owner always comes with it.” In another of his many great quotes he refers to what (even in his days) goes for “management” but isn’t at all: “Much of what we call management consists in making it difficult for people to work”.
So in the end it probably all comes down to language, which isn’t exactly a precision instrument. One of my other management heroes is Gary Hamel, and I fully sign up to his definition: “Management is a social technology, the technology of human accomplishment”. Which probably takes us closer to what you have in mind when you use the word “leadership”, right?