Sure, but how are emojis superior to this? Text is universally compatible, whereas emoji introduce compatibility and versioning issues across browsers and operating systems.
Besides the technical universality of text, it's also demographically universal. We've replaced "lol" with laughing-face-of-specific-skin-color-and-hair-style-and-gender-and-,etc., which is a worse situation than the original.
Of course "lol" is English-specific, but if you can't read another language, then what exactly would you be laughing at anyway? Different languages are always a barrier to communication, regardless of whether emoji are used.
To be specific, they introduce a lot more of such issues, but such issues were already there with plain text as well. Fonts that don't support some characters, fonts where some characters are displayed incorrectly (the whole CJK unification fiasco), fonts where some characters are not distinguished (I've run into the is-this-an-I-or-an-l issue quite a few times, personally).
People have been using things like "lol" and "lmao" since long before Unicode even existed, let alone emojis.