That's not quite what I meant by unusably bad, though that does have its own set of challenges for sure. I was just in Toronto for the first time and appreciated the designers of the Ojibwe Latin alphabet for pulling it off without diacritics.

What's happening with your example is just that the symbols chosen for the phonemic transcription are non-Latin so they're unfamiliar to read aloud and harder to type for non-speakers. What I meant was if we all wrote with all of our individual idiosyncrasies of speech without converging on a prescribed standard (a writing system separate from speech transcription).

"Amnu ge sum'm frum upsterz, gimmi u sek" but even more so, with IPA characters for all the 40-odd individual sounds of my dialect of English - then you write your response in the same level of phonetic detail. Exactly what a writing system shouldn't do.