From my 15 years being involved in startups, I would agree with this. Especially in marketing teams, which has been my area. There is no right answer which can be confirmed easily so you just have to really really care.

I will also say this is not the same as hard work. Hours and intensity is not the same. I would be considered a very successful person by most, but I have never "worked" more than 30 hours a week. But I've cared very very intensely about the results of the work that I'm doing.

You also can't expect it of employees unless you're paying them a fuck ton/have incentives.