Although you can lock down your content to only subscribers this way, it will hide your articles from Google and they will not show up in search results. Search engines rank your pages based on the content in them. If they can’t read your content, your articles will rank poorly. Your site will also not be popular in Facebook, Twitter, Linkedin etc. as no one wants to pass around an article you can’t read. It’s a steep price to pay.
It’s a good idea to set this number to a minimum of 1 to take advantage of reaching more readers in search and social media.