In past startups I would have agreed with you. When I did my first startup, I worked on it exclusively. I skipped vacations. I skipped classes (I was in school at the time). I did practically nothing else.
I burned out.
The title of CEO doesn't define me as a person. I'm just a guy that started a company. I get stressed. I need help at times. I have things I like doing unrelated to my company.
Blogging is one of those things. I blog because I love writing. Writing startup stuff for the HN community gives me purpose to that writing. It's a sweet bonus that many of our users are on HN, but that's not actually my top motivation. It's just because I like doing it.
As for 45 minute phone calls to help a friend. I'll bet the karma gets paid back nicely. But even if not, I'm not sure I could I look myself in the mirror if I became so self-important that I lacked the time to be generous.
In my experience, the difference between successful entrepreneurs who have a healthy balance between their personal and professional lives and those who don't is that the former prioritize and filter and the latter don't.
There are 24 hours in a day and each hour is precious. As the CEO of a young company, you probably have a significant amount that needs to get done each day, and you and your employees are counting on your ability to "get it done." If you're spending an hour on an "argumentative" phone call about startup philosophy with somebody who has an idea, you're trading an hour of time that can be used to benefit you or your company for an hour of time with a person who clearly prefers conflict to counsel. Let's talk about you, not your company, for a moment: in an hour, you could easily fit in a vigorous workout, take a power nap, enjoy a lunch with a friend or relative, or cook a meal for your significant other.
In reality, of course, the decision to give an hour to an individual who won't even reveal what he's working on sans NDA doesn't mean that you have an hour less work to do. It just means that you'll need to make it up, today or tomorrow, increasing the likelihood that you'll be "working late" and reducing the likelihood that you'll be able to fit in a vigorous workout, take a power nap, enjoy a lunch with a friend or relative, or cook a meal for your significant other. Activities that it should be noted benefit your overall well-being and are thus likely to have a positive impact on your performance as the leader of a company.
Obviously, I'm not saying "never take a phone call" or "don't be willing to provide advice." But as the CEO of a company with employees, you are important, and your time is valuable. Being unreasonably generous with it is not of benefit to your company, or you.