Ask HN: Can an Internet start-up outsource development of their website?

Typical Type 1N startup personality (social transformer), the founders lack technical skills and want to focus on building the business. They have asked our agency to build the site (consumer-facing front-end with search, discovery and payment, customer-facing back-end for managing data) and do some of the marketing activities (like search engine optimization and marketing).

Is that a recipe for success? I was under the impression that an internet startup needs to build its own team of employees, including a team of web developers.