This doesn’t surprise me. At all.
I’ve been known to get into pointless arguments with “big" writers on Medium about this, but I don’t do that anymore. It definitely does matter who you are — and who you aren’t.
From Medium’s point of view, though, it makes sense. Nothing succeeds like success. Why promote someone like me, a total nonentity, when you could promote someone who already has a fanbase that they could bring to Medium?
The truth is, writing has never really been about quality. People don’t even know what they like unless someone tells them. Look at the paste-faced mediocrities on the NYT bestseller list for proof of that.
It’s frustrating for those of us who keep lifting our heads to the blows of the rain. Believe me, I know. But this is what it is. And this long predates Medium. Succeeding in the arts has always been about luck or connections, and often both.