Earlier quoted context omitted.
I think the big difference between gif and emoji is that you need to see a gif to know what it represents.
You mean in terms of accessibility? The good news is that Twitter, err, X gifs already have built-in alt text. 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-...
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.