Hey Reuben -- good to see you! I've never been published in a Medium pub, but I've never submitted, so there's that. :)
I agree to a degree. The popular posts are mostly from medium's own publications, that's for sure. But at the same time, I think they are looking for a style of writing and level of quality that a lot of posts don't meet.
I guess that's their prerogative but it feels crappy to reach for a golden ring and never be able to grab it.
As Medium grows, it's reminding me more of the publishing world. Most people are going to get tossed into the rejection pile.
I guess all it leaves is to try to learn what they're looking for -- or carve out our own little corner here. Which I guess we've both done, since we're both in that top 5%.
Hope you're well! :)