Apparently emoji aren't the greatest for accessibility: https://www.tiny.cloud/blog/emojis-and-accessibility/
It may be even worse for emoticons, so that's a legitimate criticism: https://uxdesign.cc/emojis-in-accessibility-how-to-use-them-...
The bad news is that X's gifs' alt text is absolute trash most of the time. Stuff like "office stare gif" etc.
To understand a meaning of a word/emoji/gif you have to see it in context several times or look up a definition. (with emojis and gifs there is additional problem in lack of dictionaries for them). When amount of words in a language is finite or they are extending slowly (emoji) I ma able to keep up with thier meanings as opposed to gifs and memes. Which are evolving to quickly for me to keep up.
What I mean by lack of scalability is that there is insatiable demand for new emoji but only finite Unicode code space for them.
This is has even become a social/political problem, because everyone insists on equal "representation" in emoji in terms of skin color, gender, etc. We couldn't just stop at Simpsons-style yellow faces.