It depends on how they're doing it. Uber and Lyft, for example, are definitely startups under Blank's definition, because they were searching for a new model. Postmates too was new; I don't believe there was a successful delivery company that worked like they do.

If you were to start a Postmates competitor today, though, and were just doing what they did, then it wouldn't be a startup. At $250m ARR, their business model is already proven.