A useful follow-up question should have been "how are startups invited to do an interview when they're not able to describe what they're doing in two sentences?"

It does not seem possible that an application where the only description is "we're improving the way people interact" gets an invitation; so, when the interview is a little shallow (because of stress, etc.) why not start back from the application?

Or maybe the interview is not about the idea, but about the ability of the founders to communicate effectively...?