What is this person's definition of creator? They mean writing shit online for some blog or something?

That's only "middle class" in the sense that your middle class lifestyle allows you to have this as a hobby, and a few lucky people doing it make a few bucks.

The activity didn't even exist before the Internet. If you wanted to reach people with a newsletter or talk, you had to join the staff of some widely circulated publication, or get into broadcasting. Those were then middle class jobs.