I can see the appeal of doing this, and for things like UI design it makes alot of sense, but it seems too easy to cross ethical lines. Theranos basically did this, though of course on a vastly larger scale and over a longer time period. In the beginning, it's easy to tell ones self that filling in the gaps will come naturally once funding and interest are available. when there are difficulties executing on promises, it creates a choice between perpetuating the dishonesty for a low cost, or coming clean for a much higher cost. As time goes on, the feedback continues until there is some kind of breaking point. If you're going to do this, you had better be damn sure you can deliver, and have some sort of pre-determined go/no-go points to prevent things from getting out of hand.