I'm talking about the idea that you have to work so hard that it threatens or consumes everything else in your life. And no one claims that doing that is sufficient, but a lot of people claim it's necessary.
It probably is necessary if the plan is to hit a billion-dollar exit in a few years. I just think that path entails a lot of extra risk that investors overwhelmingly benefit from, and founders end up paying for in the event that things go south. And sadly, I feel that a lot of investors essentially exploit young founders who don't know enough yet to know that they're paying a very high price for a 1/10000 chance at a grand slam (making $20m in 2-5 years), when they'd be better off in almost every way by going for the 1/10 or 1/100 base hit (making $2m in 5-10 years).
And to be clear, I'm not lumping YC in with most investors here. However, YC does place a little too much emphasis on raising VC and not enough on building revenues. But that's a bubble for you :)