I showed some problems to a friend the other day. He got annoyed that he couldn't see the solutions without signing up.
I understand if we can't post problems or answer them without signing up, but what are the pros and cons for letting guests to the site see the solutions to, say, 3 problems before signing up? For that matter, do we have a guest commenter system, or are we avoiding that due to the issues of banning people who aren't signed up?
I guess my friend was annoyed that other websites require you to sign up for the smallest of tasks and he projected onto Brilliant, but it may be an interesting point.