great question... I've never wondered about it. It's a matter of limited resources. If you spend 100% of your time procrastinating in reading/commenting in hacker news then you won't have time left for building startups. However, I participating in HN can inspire you in a great way
It's a great idea.. I usually am a little confused about my career.. Sometimes I ask for advice to people I acknowledge as experts.. but it's frequently difficult to contact them