This doesn't break down anything. If a grapheme cluster is double width and you treat it as 5x because there's 5 code points in it, then you've still gotten the

This doesn't break down anything. If a grapheme cluster is double width and you treat it as 5x because there's 5 code points in it, then you've still gotten the layout wrong. You can enforce text storage length limitations to prevent infinite zalgo, but text display length limitations should always deal in extended grapheme clusters.