It surprises me how successful these companies are already. I don't think to have more than $20K MRR is any less than having a product-market fit (of a lesser scale, maybe). It's almost as if YC is not taking bets at all because the companies that are applying seem to know well what are they solving. And although it's not obvious from the article, it sounds like they scaled to that revenue pretty quick (comparatively, to say the least).
If I compare with the companies in the batch 5-6 years ago, the difference seems conspicuous. Where are the companies like Segment, AnyPerk that were struggling to find a product-market fit and presumably, were working on bad ideas? The companies who wouldn't have a good answer to what they're solving and why? There are bets, like Greo, Goosbump, which would find it hard to attain a sustainable revenue, but I think the numbers are still low.
Paul Graham used to insist that their first priority is the team, but I think they have inadvertently raised the bar. Or, it could mean that startup wisdom of building MVP, talking to users, has become mainstream to warrant the decline in the bad ideas.