Watch video lectures from MIT, they know what's up. 9 blackboards sliding on vertical rails. The lecturer doesn't have to waste time erasing boards, and the history stays up for a long time in case students fall behind on their notes.
That essay seems to focus on how copying from the blackboard can go wrong, without covering the experience since 1986 of how powerpoint and handouts go even more wrong.
This isn't to say I totally disagree. I didn't bother with many lectures in undergrad, and most of my learning happened in classes/supervisions, which I guess are equivalent to what that guy calls the "Gutenberg method". It's just that I found when the lecture was copying from a blackboard, it tended to be worthwhile going - especially since it forces a slower pace and forces you to read the material exactly.
"You wonder how on earth such a system ever arose because you know very well that nobody in his right mind would invent a system like this today. What I've heard, and I imagine that this is correct, is that it started a very long time ago, when books were rare and very expensive, and the only way to transmit information was for the teacher, who knew, to tell the students, who did not yet know. And they would write it all down and take it away with them, like a bunch of scribes. Remember, scribes were very big in the Middle Ages."