"The key thing here is social media sites don’t produce content. They merely host it. Millions of users create the content expecting it will be widely available. Locking down an API breaks that social contract."
"Merely host it" is framed here like it's no big deal. It's a huge fucking deal. Giant social networks are incredibly complicated to run, and it's not only technical aspects that make it so. You can hate these companies all you want, but let's not be ridiculous in suggesting that they offer little to no value.
Second, the idea that content producers produce all the real value on the network is incomplete. First because of the reason mentioned above: the network itself (the plumbing and operation) has tremendous value and there would be no content without it. Second, because freely provided content in itself offers no financial value, in fact it starts out as a cost (hosting and moderation). Only when monetized does this content provide financial value. I know that users don't give a shit about that or are hostile to monetization but that doesn't change the fact that a large social network needs to cover costs.
Third, the idea that any user of a social network has the right to download/access the entirety of all content ever produced on it, and this being some right or social contract...is made up bullshit. Most people have no idea what an API even is, have no weird need to do data digging, it's not a common need or expectation at all.
Fourth, the AI problem is conveniently dodged. At Stackoverflow, moderators angrily demand their data dumps back, completely ignoring the reason why they were shut down in the first place: AI. Yet nobody engages with the point that the entirety of Stackoverflow might cease to exist and become obsolete because of it. That includes all the content those moderators put so much work in to curate.
In both cases, you're on a sinking ship and protest to actively sink it faster.