I don't think it's anything new.
I just think said people now have a platform for it. Back when Network TV ruled all you had to have a moderate respectful viewpoint. Now it's all about hitting your core demographic. Even less if your on the internet just looking for some support. It's all demographics. Just like how we have more cool niche television shows, we have more well... looney political people.
I'd argue actually if you were looking for a "starting point" that it started with Republicans on a larger scale... specifically Neo-cons and a "If you don't agree with us, your with the enemy" claim. That while popular after 9/11 actually started with the cold war. (Though honestly, you'd be surprised just how common this is before then. See Federalists vs anti-federalists)
It's something that just became popular with the Left after Bush as it became something that got adopted by the "douche bag" left. Your brogressives, people who don't know anyone actually poor and Utopian if we gave it a shot it'd work instantly" types for example.
That lady actually has what I call "Super Racist Eyes". In that when I see someone with eyes like that in a video, if there is nothing suggesting what she's saying, i'm just assuming it's something hugely racist and offensive.
