The interesting thing is that applying the "Make something that you would use" model helps to dissolve some of those market unknowns. Your market is yourself. In this case I don't think snaptalent's product was something that the founders themsevles wanted to use. I would go as far to say that a great startup idea is is validated by founder(s) own problems.
Note: I said startup _idea_ and not a great _startup_.
Note: I said startup _idea_ and not a great _startup_.