Why octal notation should be used for UTF-8 (and Unicode) (2016)

This reminds me of this epic rant on x86 opcodes (sorry the gist copy; the original is no longer on archive.org, as far as I can tell). I do really wish sometimes octal were more widely used. As my dad put it, "A is not a number". But I equally get why hex won, given we standardized on eight-bit words.