I understand your point and largely agree with the idea that corporations shouldn't become de-facto governments with regard to morality/free-speech/etc. However I think it's important to acknowledge that there's a really difficult problem to solve here with regards to spam, astroturfing and harassment/trolling (if not more areas) where allowing everything that is technically legal would make most online spaces unbearable to participate in for the vast majority of people (e.g. 4chan and its ilk). And the line between moderating those things and censorship is incredibly blurry