Local and state governments in the US build most roads and are responsible for them. When the roads are built in a way that causes lots of accidents at a particular intersection (even though the people "at fault" in these accidents are the drivers themselves) people expect the government to improve the roads and reduce the harm.

So likewise, Facebook's choices in how it presented content (giving equal weight to the NYTimes and fake news generated for profit in North Macedonia) and mechanisms for maximizing likes, views, and engagement, allowed lies and nonsense to blossom on its platforms.

This isn't an issue that's restricted to any individual political party or cause, though the people in North Macedonia have been clear that "right" fake news sold much better than "left" fake news in 2016.

Facebook build the roads here and made decisions about the tools to navigate those. Users are using those tools as designed to get maximum engagement and profit, causing the propagation of memes, trolling, and lies over quality content that doesn't generate the same metrics but costs much more to produce and fact-check. That people lie isn't Facebook's fault, but like any local government, now that they know their design is contributing to problems, some expect them to address that. Same would go for the owner of an event venue that's being used weekly to promote a violent cause, even though that owner isn't responsible for the tenants, they do choose to give them space to organize.

I'm not taking a position on what exactly they should do, but I want to be clear: regardless of if there is a scapegoat effect or not, claims of Facebook's degree of measured responsibility have clear precedent.