If you're a platform, you're not responsible for what your users say (except directly illegal stuff, eg. child porn), and have no say in what stays on, or gets removed/hidden (except, again, illegal stuff).
If you're a publisher, you have a say what is posted on your site, and you carry full responsibility for all the onsite content.
Walking the line, and not wanting to take responsibility in some cases, but still deletin in other cases should be forbidden