many of these internet initialisms predate texting - I started seeing them when I first began frequenting USENET forums, which predated internet forums such as this one (this would have been during the 90s).

"Usenet is like a herd of performing elephants with diarrhea. Massive, difficult to redirect, awe-inspiring, entertaining, and a source of mind-boggling amounts of excrement when you least expect it."
— Gene Spafford, 1992