Despite all the good points made by other commenters here, I see that nobody has yet quoted the other somehow related story that appeared on these pages not long ago:
It seems interesting because the author of that post basically described how he came to YC without a developed product but only a vague and confused idea, and how his project was nonetheless accepted. He then moves on to describe how, having entered YC, he started frantically working on different projects that had nothing to do with the original idea, until he finally gave up.
Now, I wonder which could be the factors that make YC accept a non-existing project, so shaky to evaporate one hour after the interview, and reject people that at least produce and are entirely focused on a working prototype of a new product.
Because the person with the shaky and vacuous idea but excellent marketing chops has far more chance of success than the team with 500klcs written with no market validation (that team will be extremely reluctant to change course if their idea doesn't pan out with customers).
"the person with the shaky and vacuous idea but excellent marketing chops has far more chance of success than the team with 500klcs written with no market validation"
Well said - that was an incredibly painful lesson for me to learn as co-founder of a UK based startup in the first dot-com boom. We must have raised over £25 million and, to be honest, had very little market validation at any stage - and the revenues to prove it.
The factor is that they invest in people. They went as far as to accept applications of people with no idea at all a few years ago (they went back on that).
But I agree with you that a alfa stage built product tell more about a person capacity for execution than a good performance on a 10 minute interview. But maybe, both should be rejected.
How I Crashed and Burned in Y Combinator https://news.ycombinator.com/item?id=8867335
It seems interesting because the author of that post basically described how he came to YC without a developed product but only a vague and confused idea, and how his project was nonetheless accepted. He then moves on to describe how, having entered YC, he started frantically working on different projects that had nothing to do with the original idea, until he finally gave up.
Now, I wonder which could be the factors that make YC accept a non-existing project, so shaky to evaporate one hour after the interview, and reject people that at least produce and are entirely focused on a working prototype of a new product.