I think it probably depends on how far the writing system is from your own. Imagine you were coming from the English alphabet and learning Japanese. You put in

I think it probably depends on how far the writing system is from your own. Imagine you were coming from the English alphabet and learning Japanese. You put in the same number of learning hours, but in one scenario you only learn the written language, and in the other scenario only the spoken. I think you'd probably learn more from the spoken language. Spoken language is higher bandwidth. Tone of voice, melody and rhythm can convey a lot of extra information with the same words. Plus if you're getting the spoken language in real life or from video, there's probably a bunch of extra context that makes it easier to understand. Even better, if you're talking to someone willing to help you learn, they will simplify their speech and start using gestures to help you understand. I can accept that, as in the article, for someone who's spent all their time on written language spoken language will seem harder. I've split my time equally between the two and neither seems "harder" than the other. For what it's worth, my target language also uses the latin alphabet.