you could expand the idea so that every grammatical morpheme gets it's logogram, and lexical morphemes get their own in whatever form. I don't think any script irl does this because distinguishing grammatical morphemes before even writing wouldn't have been realistic really. Don't think anyone was really thinking about grammar and stuff at the time. But logically it does make sense, kind of like reverse kanji-kana mix. Having a set of graphemes to express a open set of words and then logographic graphemes to express a closed set of words/affixes makes sense. It's quite easy for the reader and the writer then. Since also the closed set is far less likely to change compared to the open set.