There is a problem when you allow your work to consume everything. Things are out of balance. That's true no matter how small or big the company is. It's not healthy for the founders or the employees to behave that way.
This isn't to say that one shouldn't spend a lot of time working on stuff or that strict insistence on a 40-hour week is always appropriate, but there is more to life than work, even when you're trying to get a startup off the ground!
Some equilibrium must be maintained, for the sanity of all. Specifically, delaying important familial developments like marriage and children or spending so much time engrossed in work that you become negligent of your familial responsibilities is absolutely an unfair trade, no matter how rich you get from the startup lottery (and realistically, you'll probably get 0 rich, which makes neglecting permanent, irrevocable relationships like family even less intelligent).
I understand that you disagree and would avoid hiring someone who is interested in work-life balance, and that's fine, but my belief is that this attitude is not good and you're not going to get good people with it. It artificially constrains your selection of talent to the naive and/or the desperate, neither of which make a good foundation for a company.