Not the original commenter, but I live in Singapore where I am surrounded by Chinese characters and several Chinese dialects. The first issue is that there isn't one "Chinese" language. Mandarin is dominant as the official language in China, but even here in SG one can still hear Cantonese, Hokkien, Hakka, and a few other dialects. While these each have unique grammars, the characters for the most part can still be understood across dialects (and for languages like Hokkien, have been mapped to those characters). Also, for Mandarin, there are very few distinct sounds (phonemes), even accounting for tones, so there are many, many more homonyms than in, say, English. The characters help disambuguate, whereas spoken or phonetically-written Mandarin relies heavily on context.