Run away because that is a terrible questions.
"I need you to deliver software from scratch, is that a problem?" should tell you a couple of things. It should tell you that for whatever reason the interviewer expects that there might be problems with you delivering an application. HOWEVER unless they know you how could they have doubts about you(let's ignore the silliness of trusting a 'yes' here.) The first thing this would make me think is that other devs have failed this 'requirement' in this company before and I would be wondering why. I would be guessing that they throw some mediocre 'specs' at a dev and expect them to poop out a fully functioning, polished app in a couple weeks. Probably with some awesome last minute modifications in the middle as well.
Developers, regardless of how little we like to admit it, do not work in a vacuum. Even an amazing developer should be part of a larger team in order to succeed. A question like the one posed above primes me, as a developer, to worry that any delays(even legitimate ones like "Technology doesn't work like that" or "You went from wanting a music playing software to wanting a robot controlling software in the middle of development") will be pinned on the dev teams and not owned by management/other teams.
A more legitimate question would be "We expect our developers to work from soup to nuts on applications. This means being highly involved with the planning, architecture, implementation and release of these softwares. Can you give me an example of a time you took a solution from drawing board to release?"
Promises like the one you describe are a terrible interview technique and I would consider them a red flag for working at that company.