That's the thing though; Chinese is a good counterexample that phonics instruction is not universal or fundamental to linguistics, but rather culturally specific. Phonetic written languages have the feature of mapping sounds to words and phonics instruction takes advantage of that.
I doubt phonics isn't fundamental to reading Chinese, though. I've learned how to read Japanese, which uses a mix of their own characters and Chinese characters. If you're reading Japanese and you don't know how to read a written word, you're basically screwed. You might be able to vaguely infer what the words mean based on the meaning associated with the characters, but that's not the same as knowing its exact definition. I guess it would also be the same for Chinese.
I think you are confusing phonics and phonetic? They are very different concepts.
I was trying to argue that Chinese readers probably do correlate sounds with letters, so I meant phonics.
It's worth a 2-year difference in the age at which kids read. On one end is Chinese. On the other end is Russian and Spanish. English sits right in the middle.
Sure but optimizations are not fundamental. It is not even clear to me if phonics instruction (invented by some teachers?) was based on linguistics (a scientific theory).