A nice discussion about UTF-8 encoding.
We see no particular reason to favor Unicode code points over Unicode grapheme clusters, code units or perhaps even words in a language for that. On the other hand, seeing UTF-8 code units (bytes) as a basic unit of text seems particularly useful for many tasks, such as parsing commonly used textual data formats. This is due to a particular feature of this encoding. Graphemes, code units, code points and other relevant Unicode terms.