"I still am super grateful that all TV shows in China have subtitles (in Chinese) because even Chinese people will get a bit confused as to what's being said without the characters specifying which of the many homophones are being pronounced" from https://www.duolingo.com/comment/7272741
I read lots of comments like this suggesting that characters are necessary, as opposed to pinyin (or kana for Japanese) only, because of ambiguity due to homophones.
Suggesting that Chinese and Japanese are "crippled" in speech, since speech and pinyin (or kana) transcriptions are equivalent! So if one is insufficient than so is the other!
I find that hard to believe. I expect that speakers adapt the language to avoid ambiguity, for example by extending words (e.g. 2-syllable words in madarin e.g. adding "zi" to some nouns) or adding more context through more sentences.
In that case however the ambiguity argument for characters falls short. Not to mention Korean supposedly has many homophones aswell, and they are just fine with hangul.
I also saw the "Lion-Eating Poet in the Stone Den" poem mentioned as an argument for characters, even though that was written to promote the use of modern vernacular in which homophones are disambiguated as needed, as opposed to old/literary Chinese.