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.
Cable went its own way with, after seening Fox News breaking through in partisan favored news, MS's Need Barrack Channel tried to do similar from the left. And then Air America ended up failing to try to be like Newscorp's offerings. I believe it is probably a matter of where people go to get info. Conservatives don't usually break through in documentaries category like the way Michael Moore does, and seem to fail miserably to do something like the Daily Show and Colbert (Seriously, I wish there was a conservative alternative to these shows, but when you have Dennis Miller turn angry old man it doesn't offer much hope). And liberals can't seem to get the cable broadcasting or radio right. Go figure.
Funny thing about Dennis Miller was that he used to be a liberal. He's a rare example of something that's pretty common. People becoming more conservative as they get older and expiernece life more. In an actual viewpoint way, not a "your older so more conservative by default" way.
I think it doesn't happen much to famous people because if they talk about their politics it becomes part of there brand. You need to keep it up as it is.
While the thing about the Colbert report and Daily show is that they actually tend to be pretty balanced. Until it's time for an election... then they go hyper partisian.
Pen and Teller's Bullshit sorta did some of that for a Libretarian style viewpoint. Downside being Pen is kind of a douchebag.
I think, as a general rule, people who are Libertarian will tend to be able to pull off humor to a greater degree than maybe someone who is conservative. Well, at least from what I have seen. There are exceptions. It is just, maybe the neocon stuff makes for bad humor, when all you do is end up mocking people who don't think militant Islam is that much of a threat, which is the main thrust of the Half Hour News Hour, which had some of the weakest comedic anchors I ever ran into. I think part of humor is that you just have to not care at all about the outcome, and not have an agenda outside of getting laughs. Yes, you have Colbert, and Jon Stewart, which end up having political views, but I believe both put getting laughs above other things.
I would say that similar happens in the area of religion or anyone on a mission. For the most part, they end up not really doing what they are supposed to do that well, because they have other things in mind. I also am not sure strong anger is a place to come from with humor, as the rage overwhelms things.
That said, I really like Brad Stine, conservative Christian comedian:
