Depressive statements would almost certainly be less common on sites that associate your identity. Probably not by a wide margin however, as I've observed people saying "Suicidal Content" with all forms communication. Some people have no filter, and truly have shitty lives. It's good to try to encourage them towards positivity, but usually futile. They can only change their outlook on life by their own effort. However, people can offer them the hope thats needed for them to want to try.