“After all, when using text-based online communication, we lack the body language or tone-of-voice cues that convey this information when we talk in person or on the phone.”

This quote is from 1982 and yet we all still fall into the same trap today

I wouldn’t say invention of the emoticon since it already existed since typewriter days in the same exact form and in print and writing for at least hundreds of years. Maybe the first recorded attempt to create a specific purpose for it on a computer system. But that seems pretty flimsy as an “invention”. But given the state of the patent system, just about everything I’m technology is an invention these days despite how long it has existed or how obvious it was.