“Just wasn’t as well known.”
“Yeah, but that’s kinda the point of the current discussion. Them being well known and well used.”
Yes, but also where they come from. Only a few expression such as “he’s 404” are truly new.
“Yes, but also where they come from”
They come from texting, obviously. That’s why they are popular, and also why we are talking about them. The average 16 year-old has probably never heard of usenet, and is only dimly aware of CB from cable airings of “Smokey and the Bandit.” “The History of Okay” or “Where Did WTF Come From?” might be interesting, but they’re really the prehistory of the current discussion.