You know, I was trying to remember if anyone from Usenet did similarly, but I couldn't think of anyone.

I was a bit post-Great Renaming into well post-Eternal September. And we may have followed different groups.

The style arises spontaneously in isolated individuals and groups of course (at least since e. e. cummings!), but it was pervasive-to-universal on IRC and MUDs.

I do wonder how it trickled into there though. The most boring answer is probably the correct one. it was slightly easier to type and kids are naturally flexible.