Though I support Reddit in its (very belated) actions here, I disagree with your statement.

Restrictions on free speech and dissent ... or the overwhelming of channels, forums, and archives with propaganda and disinformation ... are both characteristics of abusive, power, regardless of its foundation. The origins of free speech princples emerged in response to religious and monarchical governmental abuses, for the most part (with some role played by lesser nobles and interests).

With numerous commercial firms existing at scales which rival entire countries, the "private property" defence against any and all limitations on censorship simply isn't supportable. That said, a reasonable and principled policy with review, oversight, and appeals processes would be useful. Ultimately I see government regulation as a very likely necessity for communications platforms operating at significant scale.