I do believe web sites need to be indemnified against what users post. But I think there needs to be new laws about what and how it can sensor posts if it chooses to do so. This should similarly apply for app stores. Apps are speech; both art and functional. Also they need to be regulated as to what is in their shirkwrap licenses and how they can revise them after the fact only to their benefit. App stores can not block installation of alternative app stores or actively hinder their functioning. Nor can you require compensation for alternative app stores. No more walled gardens.
Spam can obviously can be censored as well as malicious content like trojans, viruses, and spyware. There needs to be some regulation on this and users need to be able to override it if they so choose.
But speech and criticism needs to be free on these mass communication platforms which if one is not participating on they are effectively silenced in public speech. There needs to be clear and reasonable regulation when it comes to censoring public speech and remedies for taking matters to a real court with monetary and legal relief.
How can this be imposed on private platforms? By putting strings on indemnification. If you insist your private then you are completely responsible for everything posted which is only reasonable. If your editorializing everything then you don't need to be indemnified for what people post since your reviewing all posts yourself. This would be effective with app stores as well since companies can not be totally sure of apps and would not want to be sued over them doing malicious things.