Ink runs when dragged over by a right handed writer moving left.
No ink will run as long as you hold your ink brush correctly, see this video for a demonstration of traditional Japanese handwriting, top to bottom, right to left, brush held comfortably by a right handed writer, no ink dragged over:
If you’re trying to make an argument that brushes were superior to quills, I could buy that. But it still seems like a point in favor of right to left, that the opposite requires a higher minimum skill level.
No ink will run as long as you hold your ink brush correctly, see this video for a demonstration of traditional Japanese handwriting, top to bottom, right to left, brush held comfortably by a right handed writer, no ink dragged over:
https://www.youtube.com/watch?v=IwzJtUAzcpM
If you’re trying to make an argument that brushes were superior to quills, I could buy that. But it still seems like a point in favor of right to left, that the opposite requires a higher minimum skill level.