Well, for one, I imagine the "network" provided by YC is less valuable to late stage companies than it is to early stage, so YC probably found they were not abl

Well, for one, I imagine the "network" provided by YC is less valuable to late stage companies than it is to early stage, so YC probably found they were not able to bring as much value. Second, the amount of capital needed to invest in later stages is much higher, and with companies delaying IPO, they would be tying up capital for much longer than they probably expected originally. I have no insight into YC, this is just my guess as to how it is different.