Facebook: social over random content. Streaming services: commissioned content. Arguably non-monetized YouTube: where its used simply for its utility of serving video.

Yes, but all of this "content"* comes from contributors, who else ??

Streaming services (you mean 5he likes of Netflix ?) are arguably not platforms, because they are much closer to distributors or even publishers (rather than just editors, sometimes), with all the extra legal issues and contract-signing that come with that.

*"content" is really corporate-speak, I would hate my works to be called that :

https://craphound.com/content/Cory_Doctorow_-_Content.html#1

Netflix. The New York Times.