I disagree, I didn't put words in the author's mouth. I didn't chose the questions or the framing. I also disagree, it is out of line to suggest that. Startups existed before YC. YC does not hold a monopoly on determining or ensuring success. Their "rejection" letter alludes to this fact.

YC has a tremendous amount of experience and their intuition and insight I'm sure leads to better decisions regarding startups, but they're in no way infallible.

I suppose my main point is that there are plenty of good companies that are fund worthy that don't get into YC for various reasons. One of those reasons being that YC doesn't have the time or resources to take them in. The YC model has been successful but there is still an underserved market here and that is why others are popping up, not that there is a bubble necessarily as the author suggests. There's no reason why angels wouldn't "invest in companies that are not vetted by Y Combinator?".