That's was one thing that seemed odd to me. Take 15-45 minutes to write a note. Or, y'know, be present for 15-45 minutes right there in person.
However I suspect this is less about time management and more about communication styles: this person is a writer. They communicate better when writing.
As they said in the piece, they're also doing thinking while writing. A lot of this thinking is something that isn't going to happen if you're there in person. And the other advantage they mentioned is that it frees up their in-person conversation time for more interesting and intimate conservations.
However I suspect this is less about time management and more about communication styles: this person is a writer. They communicate better when writing.