You would be surprised. Publishing doesn’t work like the old days. Publishers today don’t really want to take on new writers unless they have their own audience waiting in the wings.
Even when they do take on a relatively unknown, they don’t do much marketing. They get better returns putting their marketing dollars into a known author. So the unknown ones have to do their own marketing if they ever want to see royalties.
You would be astounded to know how many published authors are writing here on Medium. Most of them write for Medium’s publications.