You would have thought that logging in would not be an issue, but we previously had a private site where it was necessary to log in and we found as people only use our site infrequently they were forever contacting me saying they couldn't remember log ins! We eventually took the decision to make it public and the number of people using the site has increased dramatically.
As the function is there would it be possible for you to please activate it for us on this one site? We will be carefully monitoring and moderating and we will obviously disable the function should we start to have problems with anything 'dodgy'
If this function is really not available, then possibly you should amend the information on your site, as it gives the impression that although not advised it is a possible feature?
very many thanks