> what makes Facebook special in this chain such that it is their responsibility to perform the filtering
Distribution. Each step until Facebook doesn't involve sharing with others, it's between you and a machine until that
Distribution. Each step until Facebook doesn't involve sharing with others, it's between you and a machine until that
So maybe you mean more like the discoverability for people is provided by Facebook. But would this then not also imply that search engines have to filter their search results? And in both cases I could argue that the service provider preventing the upload would also prevent discoverability on Facebook, and not only on Facebook but on the entire internet at once.
Facebook hosts the content and makes it available to the public. That is why they are special. None of the other steps do both