Building a startup team based on skills is a lot like the casting activity in the film industry. Those responsible for casting a movie will look at the character in the plot, and try to find actors that they know have the ability to play the role. Though there is also a secondary look at how these actors look together on film, their onscreen chemistry. So the casting activity is actually a casting of the ensemble, not just the individual actors.
When does a startup stop being a startup? As a founder, why should you care?
Startup is a phase. Eventually a company will and should grow out of that phase. Normally in 2-3 years. To remain in Startup mode is actually to invite atrophy. A company that has emerged to a point where they have a loyal customer base and a viable business model does need to adopt some traditional customer facing processes for sales, marketing, delivery and after-sales services. Otherwise, they risk losing that customer base.