So does Don Knuth. So does Don Hopkins, the former director of health programs for the Carter Center and spent years leading the effort to eradicate Guinea worm. So devoted to his task, he didn't even give his kids his cell phone number when he traveled to Africa.

I can't speak for the current US President, but there are a lot of people who are perfectly capable of reading email, but for whom the task would distract them from more important uses of their time.