I think we're at a place where using the phrases "Art of ...", "Science of...", and "Art and Science of ..." are not interpreted with the literal definitions of art or science in mind. Typically, in colloquial (as opposed to formal) writing, "art" comes with an understanding of "all the steps haven't been quantified and some intuition is involved" and "science" tends to be "here are the steps to take and the items to observe and the things to change in response."

So I disagree: there is Art and Science to, well, most things; including leading projects.