Their loss, eh? This would be like “The Atlantic” saying, without even looking at the author’s submission, “Oh, you had a story published in the community college journal? How cute. No thanks.” Such snobbery. It is, unfortunately, a bit common between some writers. That sort of nonsense almost put me off writing, 30 or 40 years ago — until I realized that was just a childish segment of non-working writers. Real writers didn’t waste their time on such silliness.
Now, there is still a bit of a stigma against self-published writers of all stripes, and as unfair as it is, anyone who is on Medium — playing that game — is hopelessly lacking in self-awareness.