I mean, yes this is true, but I think the point was that if someone isn't fluent in Korean, and isn't familiar enough with the alphabet, they'll not feel qualified to say if to a native Korean it would look good.

I studied Japanese for many years, and know the two phonographic alphabets quite well, yet I'd still defer to my native Japanese speaking friends when it came to determining if something was legible. I've found that things that are legible to me are sometimes not to them, and vice versa enough that I suspect a font designer with any humility would be quite uncomfortable designing a font with characters they weren't very familiar with.