Reply #95: "We have to discuss politics to learn from each other."

[suffragette]

That's exactly the point. In anything, we need to have discussion to learn from each other and politics is no exception. But that taboo is there under the guise of being polite and we here it somewhere along the way when we grow up. When I think about it, I can't even pinpoint when I first heard it, though I think it was when I was young.
Maybe it is more prevalent in conservative strongholds, though I'm not from one and still heard it. But it does take hold more in mixed political company and I've also been in the same position as you in that setting, sometimes biting my tongue, sometimes moving away and sometimes (though not as often as I should) challenging what was said, either gently or not. In that same setting, people feel free to bring up financial or career questions and to argue vociferously about sports preferences among other topics.
I've heard before that this is different in other cultures, in some it's finances that's taboo to bring up while political discourse is encouraged. It's a shift that would benefit us all if it were to take place here. Maybe the blogs and many discussion forums can help create that shift. I think politics are coming up more and more often in these venues, even the ones that aren't overtly political. As people feel more comfortable with engaging more and more in this way in virtual space, maybe it will start to transfer over into more open discussion in the world.