I read a post recently saying that a DP also being a steadicam op, or movi operator, or editor, or director, is the death of them.
I kind of disagree.
I think from the directing I do, the more I learn the needs of the director when I am DPing. Also the value of good directing, seeing how difficult it really is. How to communicate, how to understand this.
And by having a DP know how to do other things, like sound, you understand what the sound mixer needs. And of gaffing and gripping, same thing, you understand the emotional and physical weight of saying to someone "can you move that 18k please over there."
It's also good to speak in everyone's familiar terms, and to understand what each crew position does and needs.
I agree though you can waste your hours a day being focused on too many things, but at the end of the day, how much of our free time is wasted on facebook or instagram or god knows what else. There is plenty of time in the day to learn as much as you want.
Learning itself, and breaking yourself free of one's specific focus can regenerate the brain I feel, and make it more exciting when you bring what you learn to what you are doing.