If you're not a domain expert everything you come up with will collapse under efficiency arguments. Such as "if this made sense someone would have done it".
Much of expertise is knowing what experts themselves think. That's why you can answer the question of why it isn't already there.
I have a question though. If you need to be a domain expert, how can there be so much focus on young founders? Is that a different category of investment, people who happen to have a lead into an emerging industry like social networks?
Young founders are often in B2C and capital-light. They are judged (almost) purely on growth metrics. Series A negotiation can drag on for months, and its hard to fake 100% month-on-month growth.
The B2B will usually be more experienced insiders with deep domain knowledge, and excellent references.
EDIT: everything is relative. If you are a brilliant PHD in ML then you can be 25 AND a domain expert AND go in to a capital-heavy B2B sector.