It's great advice not to be that type of asshole when you've done nothing, but it's also true that one of the pillars of YC success is someone who doesn't necessarily know your niche telling you what you're doing right/wrong.

Sometimes advice is about the niche, sometimes it's about time management, time-to-market, hiring, firing, whatever. The answer has to be about balance - sometimes you know better, sometimes you don't.