I might be wrong in this, but YC is not in the business of precisely predicting the future. It is within the business of creating and curating a network. Let me explain why, most VC funds are organised around a theme - they have a particular industry that they look at and then they create a narrow window around it and predict that by time X, this will be worth a lot, so they'll find people to capture Y. YC on the other hand has a thesis focussed around its own network. Yes, they seem to fund around general trends, but mostly they give smart people money and get out of their way.
Let's unpack that. Let's say you have 20 smart people and you want to guide them, give them resources, and then stay out of their way. What's the best way to do that? Well, the best way seems to be to create a peer group - a band of sister + brothers - who have set out to do something extraordinary. And then let common stress signals bake in the ties.
Now let's assume that you have these ties between people i.e. they become good friends. What happens when one of them achieves success? Well they'll start getting approached by people asking for help too. Young people, lost, and trying to do something extraordinary. Where do you think they'll refer these people on to?
So what started out as a support group, suddenly starts growing organically, and YC starts getting its pick of founders provided that the original people they seed it with are the right kind. The kind of people who attract other intelligent people. And identifying that is literally the core job of YC, which seems to be jl's job...
Is it unfair to say that she made YC given that?