To me, this seems a bit too simple and cheap. There a lot of people who want to write, who feel a real need to write, and are hungry for advice. I think it verges on elitist to tell people not to write about writing.
After all, if people who know how to write stop writing about writing, the first people to lose out are people looking for advice on how to write better. And telling people to “just write” is bullshit — utter bullshit. That’s like telling a basketball hopeful to “just shoot”. Without advice and guidance, “just working” is going to do precisely nill for a lot of people.
I understand the frustration with the plethora of content on Medium that seems to just be the same old stuff. However, I think we need to be a bit more compassionate toward the people writing it. They want their voice to be heard — just like you. Just because they’re practicing some meta-writing doesn’t mean they’re doing some disservice to writing.