That's a fallacy in the broad sense. I've had investors who had very different goals for my company than I did. Investors, YC included, are after liquidity events.. plain and simple. As a founder, that's not always the case (and the desired timeline is almost always drastically different).
In the YC case, as a relatively small (very) early stage investor... they might very well benefit from a lot of very quick exits. Before additional investor dollars and the resulting dilution that accompanies it. It's plausible that this deal with Facebook is designed to achieve that. Essentially giving Facebook early insight into these companies and that ability to pick them up for cheap ($2M-$10M), which might actually be advantageous for YC.
I'm not saying that's what is happening here. I really have no idea. I'm merely point out that Calcanais might have a strong point.
I think there are a lot more YC founders anxious to make a smaller exit than YC partners anxious to see small exits. IMO the problem of YC pushing companies to accept liquidity simply doesn't exit.
they might very well benefit from a lot of very quick exits
I fail to see how. Before they closed their Sequoia round, you could argue that smaller exits help YC keep afloat. With millions in the bank from outside funding, YC is beyond the point of trying to keep itself afloat.