Stories about "Trump's unprecedented use of social media" could be on-topic. That doesn't necessarily make "Trump stories"
in general on-topic.
Stories about "the effect that social media as a whole has had on the American political landscape" could be on-topic. That doesn't necessarily make US politics in general on-topic.
Stories about "the influence of social media platforms and their ability to manipulate public perception" could be on-topic. That doesn't necessarily make stories about "fake news" in general on-topic.
Stories about the Wikileaks organisation could be on-topic. That doesn't necessarily make stories derived from the contents of particular leaks on-topic.
Stories about the DNC data leak could be on-topic. That doesn't necessarily make stories derived from the contents of the DNC data leak on-topic.
Stories about gender and racial disparity in tech and programming could be on-topic. That doesn't necessarily make stories about gender and racial disparity in general on-topic.
Stories about an Antifa or BLM hacking group could be on-topic. That doesn't neccessarily make stories about Antifa or BLM in general on-topic.
Personally, I don't find this distinction particularly hard. As for "bias", I've seen sentiments on this site that could broadly be categorised as Republican, Democrat, Libertarian, Green, etc. Of course, there is a heavy political bias, but I'd say it's generally just "US-centric" (which is to be expected, as this is a US site); e.g. as a UK citizen I find some of the comments very bizarre (usually anything involving guns, healthcare, abortion, etc.). It can still be interesting, and if not I can just collapse the thread or close the page.