What was the reason for writing this way on stone? It can't be to keep text aligned - you can just walk to the left and keep going, and the text will stay aligned just as well as if you'd been writing right-to-left.
What is the reason for writing always in the same direction? I don't ask this as a joke: is there seriously a cognitive advantage to having to pass your eye all the way back to the beginning of the next line (whether you read right-left, left-right or top-bottom) vs immediately dropping down and continue reading? On the other hand I spent a lot of time in high school and university reading pictures of boustrophedon g…
Only about half the glyphs to recognize. Being able to skip further down the "page" and trivially continue reading. Being able to rapidly scan a line of text.
I guess this is all predicated on a mostly literate populace with a lot of reading material. You probably don't need to rapidly scan a wall carving extolling the virtues of your God-Emperor and recording all of his battle victories, unless you're trying to win a bar-bet. ("I'm telling you, he beheaded TWELVE infidels with a single swing!" "Yeah, well, find it on the wall and I'll buy you a beer.")