of course sites have their own policies. not sure i agree that "there are plenty of spaces to discuss such things". don't see many examples in this thread; only "gab" is mentioned as being tolerant of controversial/illegal subjects, and man, is it getting blasted for it. wikipedia describes it as a "haven for neo-nazis". yikes!
isn't there room for something simpler?
for example here on HN, was a discussion about staying motivated to work on challenging stuff. a comment about cocaine was deleted. well, the truth is, plenty of lawyers straight-up depend on that stuff, the way programmers depend on JAVA. why is this comment deleted? because it's bad? illegal? might tempt some kids to try it and ruin their life? whatever the reason for the censorship, the truth is being hidden aka “showdead".
so there are a couple of inter-related things going on here that i'd love to see addressed by a community, if not this community:
1. transparency. lobsters does this well. if there is going to be moderation and censorship, be transparent about it, and about why its happening. every change a mod makes on lobsters includes a "commit message" explaining the action. conversely users on hn get banned and may not even know..
2. free speech is about more than providing a space for neo-nazis and trolls and otherwise people who belong in jail or segregated from society. i think the analog is the academic vs the corporate world. we have scientists using up public money to think about stuff that may never have any actual value to society. but we enshrine their ability to do that work because its necessary in order to make discoveries. similarly, actual thought, genuine knowledge, which should be the end-goal of any discussion that is not merely rhetoric, ought to be concerned with arriving at some kind of truth or truthful conclusion. we can't do that if we are too broad with our censorship, as evidenced with the cocaine comment. pretending cocaine doesn't exist doesn't make you right when everything you've read says that tea is the most powerful stimulant.
3. to krapps point about petty dictators -- yes, indeed, and that's important so that communities can have identities and topics and focus and not just decay into noise. but it seems that providers -- you mention google, hosting companies, ISPs, etc -- all play it safe, and are absolutely not interested in participating in the free speech debate at all. thus they are very much gatekeepers. no, you cannot get popular online while being blacklisted on google, or kicked around from one host to another (at least it must be an order of magnitude more difficult, esp for niche communities). even self-hosting is not really a viable option. academic institutions are an option here, but i do worry about it changing in the future.