It's the case for about 80% of characters by my very unscientific estimate -- there are of course some logograms and ideographs left even if the meanings have a

It's the case for about 80% of characters by my very unscientific estimate -- there are of course some logograms and ideographs left even if the meanings have also shifted. But the difference (and maybe one awkward part) in written non-Mandarin today is the flagrant use of 口 + similar sounding word with zero meaning, just as foreign words are sometimes imported for pure sound reasons. Chinese is far from a pure language, but I'd argue that whatever "rules" that created 清，情，晴 are better attempts at capturing both sound and meaning.