Well... not that the advice isn't solid, and she's a good teacher for driving this point into the programmer student's minds. But saying no sign is a bit extreme, there is some level of design in any natural language. Icelandic has a committee that decides on new words. Instead of using foreign loan words they largely make up their own new Icelandic words when needed for new concepts. In German the spelling is centrally planned and gets reformed every other year. Which is why German words are mostly spelled as they're pronounced, as opposed to English. Chinese grammar is super simple and logical. I don't know if this is due to design but it wouldn't surprise me if there had been some reforms in the past. Especially since standard Chinese used to be a somewhat artificial literary language. And speaking of writing: All alphabets are designed of course. Korean is a great example for a really clever and logical design. The reading and writing in turn will have had an influence on the way we think and speak, since it formalized and standardized languages.