There are really two ways to impress a super early investor like ycombinator: 1) Have some admirable amount of "traction", if you've managed to get 20,000 user

There are really two ways to impress a super early investor like ycombinator: 1) Have some admirable amount of "traction", if you've managed to get 20,000 users for a product, that's pretty cool. 2) Be able to articulate why and how you're going to get traction, where the pool of interested users will come from, and how much money that could be worth in the best case. YC does a ton with non-consumer startups (like mine), but we still have the same two hurdles to overcome. What you're probably sensing is that the viral features you can build into consumer startups are easy answers to some of their questions, though chicken and egg problems come up in most of those cases.