I see where you're coming from, but I disagree on some specifics, especially regarding bytes.

Most people care about the length of a string in terms of the number of characters.

Treating it as a proxy for the number of bytes has been incorrect ever since UTF-8 became the norm (basically forever), and if you're dealing with anything beyond ASCII (which you really should, since East Asian users alone number in the billions).

Same goes to the "string width".

Yes, Unicode scalar values can combine into a single glyph and cause discrepancies, as the article mentions, but that is a much rarer edge case than simply handling non-ASCII text.