"You should be willing to make this startup the main focus of your life"

I can't help but notice that one of the links on the YC jobs page (viewable above at news.yc/jobs) says that prospective engineers should "be willing to make this startup the main focus of your life". Is this reasonable?

I know HN has been through several equity for non-founders discussions this quarter; there's certainly room for continued debate on whether or not early hires deserve a lot of equity.

That leads me to my concern with the requirement in this post's title: Is it reasonable to expect anyone to build their life around an employer? Unless the employee is a major shareholder (i.e. cofounder) this seems like it's asking too much. In this case the prospective engineer would be the first non-founder employee. Perhaps they'd be eligible for double-digit equity? If so, that pretty much makes them a cofounder and invalidates most of the above questions.