x.com/arctotherium42/status/2086423122492665967

This sentence is too absolute to be accurate. Long before 2015, major Western platforms already had moderation rules against many categories of non-criminal content.

• Facebook said in March 2015 that its Community Standards update was not a policy change, but added clarity to rules that were already being enforced. Facebook wrote that the guidance on "bullying and harassment, ... nudity, hate speech, and violence" was "consistent with how we've applied our standards in the past," and explicitly said "Hate speech has always been banned on Facebook." That directly contradicts the idea that pre-2015 platform rules were limited to "actual criminal activity."
• Twitter likewise had anti-abuse enforcement before 2015. In a December 2, 2014 post, Twitter described content that "violates our rules around harassment and abuse" and discussed faster review and "new enforcement procedures for abusive accounts."
• Google/YouTube also had non-criminal content rules before 2015. In September 2014, Google's public policy blog said it worked to combat hateful content on platforms including YouTube, and told users to report policy violations such as "hate speech" or "harassment."

Because these are all categories of lawful-but-disallowed content, the claim that the pre-2015 Western internet was "almost entirely free and open, except for actual criminal activity" is factually incorrect.