I think the difference is that in the past there were many publishers. You're right that editorialising and censorship has been going on forever, but in the past much of it was kind of (unintentionally) decentralized.

Not that it was always perfect or anything, but this is a key difference. You can get content out there without going through Facebook/Google, but it's much harder. It's like the postal service doing the censorship.

The challenges faced by Facebook and Google are also substantial, although most of these revolve around user-generated content, a bit different from publisher-generated content. Maybe it shouldn't treat them as identical.