I disagree with the one you replied to. I instantly understood what it was about, and with the example it solidified my thoughts.
Also, common questions like "where are my documents stored", "is it secure", "how do I share the result and who can see it"... remain unanswered.
The only parts of the site that should be hidden behind the sign up process are those that only affect logged-in users; learning about the site and business is not one of those. Most of that information does not need to be located at the front page itself, but there must be a link allowing the user to find it.