Right. And 90% of the writing I do today is writing out notes to myself while I plan or work through problems in my notebook. That kind of writing doesn’t need to be legible to anyone else.
Shorthand was never a commonly used technology by "normal" people and as I understand it even proficient users would not use it for their personal notes. It was used in situations where minimizing writing time was important, and then transcribed into standard writing shortly afterwards, while it was still fresh in their minds. It's not a replacement for writing, it's a replacement for a tape recorder.