Still, they have the same purpose.

Emoji were easy to implement in Japanese because they already had an input system, and all the UI to turn phonetic into single characters: はなー＞花. From there it's trivial to implement はなー＞ as well.

They become easier to implement in European languages as we got predictions, and touch screens, but until then implementing emoji would have been much more complex.

The point is, although emoji as known now come with rich selection of emoticons, same didn't apply to earlier Japanese emoji sets.

"Emoji present on the Sharp PI-4000 (1994)" from the article shows 20+ animals(12 from Chinese calendar), 9 relatives(grandpa, baby, so on), 3 types of alcohol(beer, sake, cocktail), and two smileys, one happy and one angry, out of 160 symbols. That's quite unlike typical non-Japanese emoticon sets before iOS emoji.

Granted, the Sharp pocket computer emoji wouldn't have been designed for chat, so there would have been less need for emoticons - but if you look at the list of emoji implemented in phones from NTT doCoMo and J-PHONE had back then linked in the article, there are just 5 each, neither even having a single circular smiley.

I'm not sure that I agree. Maybe the kaomoji were used for second/third person (I haven't used them much), but :) :( :D and friends aren't any less first person expressions than most emoji are.