The counter-argument would be that the person could just use the pinyin or use a digital device to get them the characters. But as the article pointed out, those are both modern conveniences. Less than 100 years old both. The script absolutely gives no clues otherwise.
Let's put it this way: We know what ancient might egyptian (most likely) sounds like because they gave their writting system the uniliterals, which are pronunciation guides for complex words. We know that they said waw, and we know what a waw sounds like. They did this probably so they would not to explode their character count from hundreds to thousands.
All three PhD's were perfectly capable of communicating the word for sneeze and also recognize it in writting. They just couldn't write it exactly.
I don't think it has a slowing effect. Except maybe by adding annoying/useless classes for mid/primary students - which is just par for course everywhere else. I can name 3 objectively completely useless classes from my european youth (plus one in college) that were only there because 'culture'.
Let's put it this way: We know what ancient might egyptian (most likely) sounds like because they gave their writting system the uniliterals, which are pronunciation guides for complex words. We know that they said waw, and we know what a waw sounds like. They did this probably so they would not to explode their character count from hundreds to thousands.