If it had been invite only I would never have been able to join HN or make the contributions that I have (minor though they may be). I just don't run in the sa

If it had been invite only I would never have been able to join HN or make the contributions that I have (minor though they may be). I just don't run in the same circles and don't have some other web presence (a blog for example) that might serve as credentials. Invite-only would put a real hard-limit on growth. Is growth the key problem or is it something slightly different?