I wonder if there is any kind of selection effect in this. YC attracts a lot of attention and helps steer opinions about what are attractive investment opportun

I wonder if there is any kind of selection effect in this. YC attracts a lot of attention and helps steer opinions about what are attractive investment opportunities. If YC (for whatever reason) tends not to like companies that pass through multiple accelerators, maybe that has a side effect of making other people also not like them (just because YC doesn't) and eventually to build up some biases or (potentially unjustified) extra skepticism about them, and over time it means a more difficult funding landscape once you've attended multiple accelerators, regardless of the quality of the company. The post says that YC's reasoning is that conditioned on knowledge that the company attended multiple accelerators, YC expects to see more significant progress. I think this eliminates any usefulness of doing a randomized experiment on YC applications, where the property of previous accelerator attendance is hidden and we just observe whether YC would accept them or not (meaning, their fundamentals are good enough to be accepted). Instead, YC is saying that fundamentals that look good enough to be accepted are actually not good enough if you've been through an accelerator. On one hand I understand what they are saying, but on the other hand I also think that however an application comes to be sitting in front of your eyeballs shouldn't necessarily matter. It seems odd to me that the criteria for entry would be path dependent and the goalposts could move back or forth depending not on what the current state of your company is, but on how it arrived at that current state. Please note this is not a criticism. I am not a successful start-up accelerator. Just observations about this seeming counter-intuitive to me.